Merge pull request #674 from Noggog/Nullability-Flavor-Bootcamp

Nullability flavor bootcamp

.editorconfig

@@ -122,3 +122,66 @@ csharp_preserve_single_line_blocks = true
 dotnet_diagnostic.CS4014.severity = error
 # CS1998: Async function does not contain await
 dotnet_diagnostic.CS1998.severity = silent
+
+###############################
+# C# Nullability              #
+###############################
+# CS8602: Dereference of a possibly null reference.
+dotnet_diagnostic.CS8602.severity = error
+
+# CS8600: Converting null literal or possible null value to non-nullable type.
+dotnet_diagnostic.CS8600.severity = error
+
+# CS8619: Nullability of reference types in value doesn't match target type.
+dotnet_diagnostic.CS8619.severity = error
+
+# CS8603: Possible null reference return.
+dotnet_diagnostic.CS8603.severity = error
+
+# CS8625: Cannot convert null literal to non-nullable reference type.
+dotnet_diagnostic.CS8625.severity = error
+
+# CS8653: A default expression introduces a null value for a type parameter.
+dotnet_diagnostic.CS8653.severity = silent
+
+# CS8601: Possible null reference assignment.
+dotnet_diagnostic.CS8601.severity = error
+
+# CS8604: Possible null reference argument.
+dotnet_diagnostic.CS8604.severity = error
+
+# CS8622: Nullability of reference types in type of parameter doesn't match the target delegate.
+dotnet_diagnostic.CS8622.severity = error
+
+# CS8610: Nullability of reference types in type of parameter doesn't match overridden member.
+dotnet_diagnostic.CS8610.severity = error
+
+# CS8618: Non-nullable field is uninitialized. Consider declaring as nullable.
+dotnet_diagnostic.CS8618.severity = error
+
+# CS8629: Nullable value type may be null.
+dotnet_diagnostic.CS8629.severity = error
+
+# CS8620: Argument cannot be used for parameter due to differences in the nullability of reference types.
+dotnet_diagnostic.CS8620.severity = error
+
+# CS8614: Nullability of reference types in type of parameter doesn't match implicitly implemented member.
+dotnet_diagnostic.CS8614.severity = error
+
+# CS8617: Nullability of reference types in type of parameter doesn't match implemented member.
+dotnet_diagnostic.CS8617.severity = error
+
+# CS8611: Nullability of reference types in type of parameter doesn't match partial method declaration.
+dotnet_diagnostic.CS8611.severity = error
+
+# CS8597: Thrown value may be null.
+dotnet_diagnostic.CS8597.severity = error
+
+# CS8609: Nullability of reference types in return type doesn't match overridden member.
+dotnet_diagnostic.CS8609.severity = error
+
+# CS8714: The type cannot be used as type parameter in the generic type or method. Nullability of type argument doesn't match 'notnull' constraint.
+dotnet_diagnostic.CS8714.severity = error
+
+# CS8605: Unboxing a possibly null value.
+dotnet_diagnostic.CS8605.severity = error

Wabbajack.Common/AsyncBlockingCollection.cs

@@ -9,14 +9,9 @@ namespace Wabbajack.Common
 {
     public class AsyncBlockingCollection<T> : IDisposable
     {
-        private readonly ConcurrentQueue<T> _collection;
+        private readonly ConcurrentQueue<T> _collection = new ConcurrentQueue<T>();
         private bool isDisposed = false;
         
-        public AsyncBlockingCollection()
-        {
-            _collection = new ConcurrentQueue<T>();
-        }
-        
         public void Add(T val)
         {
             _collection.Enqueue(val);

Wabbajack.Common/CLI.cs

@@ -10,10 +10,10 @@ namespace Wabbajack.Common
         public static bool NoSettings { get; set; }
 
         [CLIOptions("apikey", HelpText = "Manually input an Nexus api key")]
-        public static string ApiKey { get; set; }
+        public static string? ApiKey { get; set; }
 
         [CLIOptions("install", ShortOption = 'i', HelpText = "Install a ModList via CLI")]
-        public static string InstallPath { get; set; }
+        public static string? InstallPath { get; set; }
 
         [CLIOptions("help", ShortOption = 'h', HelpText = "Display this message")]
         public static bool Help { get; set; }
@@ -94,7 +94,7 @@ namespace Wabbajack.Common
         // -shortOption, short name of the option. Eg: -o
         public char ShortOption;
         // text to be displayed when --help is called
-        public string HelpText;
+        public string HelpText = string.Empty;
 
         public CLIOptions(string option)
         {

Wabbajack.Common/DynamicIniData.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Dynamic;
 using System.Text;
 using System.Text.RegularExpressions;
@@ -35,7 +36,7 @@ namespace Wabbajack.Common
             return true;
         }
         
-        public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object result)
+        public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, [MaybeNullWhen(false)] out object result)
         {
             if (indexes.Length > 1)
             {
@@ -114,7 +115,7 @@ namespace Wabbajack.Common
             return Encoding.UTF8.GetString(acc.ToArray());
         }
 
-        public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object result)
+        public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, [MaybeNullWhen(false)] out object result)
         {
             if (indexes.Length > 1)
             {

Wabbajack.Common/Enumerable.cs

@@ -1,14 +0,0 @@
-using System.Collections.Generic;
-
-namespace Wabbajack.Common
-{
-    public static partial class Utils
-    {
-        public static IEnumerable<T> Cons<T>(this IEnumerable<T> coll, T next)
-        {
-            yield return next;
-            foreach (var itm in coll) yield return itm;
-        }
-        
-    }
-}

Wabbajack.Common/Error States/ErrorResponse.cs

@@ -8,7 +8,7 @@ namespace Wabbajack
         public readonly static ErrorResponse Failure = new ErrorResponse();
 
         public bool Succeeded { get; }
-        public Exception Exception { get; }
+        public Exception? Exception { get; }
         private readonly string _reason;
 
         public bool Failed => !Succeeded;
@@ -32,15 +32,15 @@ namespace Wabbajack
         }
 
         bool IErrorResponse.Succeeded => Succeeded;
-        Exception IErrorResponse.Exception => Exception;
+        Exception? IErrorResponse.Exception => Exception;
 
         private ErrorResponse(
             bool succeeded,
-            string reason = null,
+            string? reason = null,
-            Exception ex = null)
+            Exception? ex = null)
         {
             Succeeded = succeeded;
-            _reason = reason;
+            _reason = reason ?? string.Empty;
             Exception = ex;
         }
 
@@ -60,7 +60,7 @@ namespace Wabbajack
             return new ErrorResponse(true, reason);
         }
 
-        public static ErrorResponse Fail(string reason, Exception ex = null)
+        public static ErrorResponse Fail(string reason, Exception? ex = null)
         {
             return new ErrorResponse(false, reason: reason, ex: ex);
         }
@@ -75,7 +75,7 @@ namespace Wabbajack
             return new ErrorResponse(false);
         }
 
-        public static ErrorResponse Create(bool successful, string reason = null)
+        public static ErrorResponse Create(bool successful, string? reason = null)
         {
             return new ErrorResponse(successful, reason);
         }
@@ -91,7 +91,7 @@ namespace Wabbajack
     public interface IErrorResponse
     {
         bool Succeeded { get; }
-        Exception Exception { get; }
+        Exception? Exception { get; }
         string Reason { get; }
     }
 }

Wabbajack.Common/Error States/GetResponse.cs

@@ -8,7 +8,7 @@ namespace Wabbajack
 
         public readonly T Value;
         public readonly bool Succeeded;
-        public readonly Exception Exception;
+        public readonly Exception? Exception;
         private readonly string _reason;
 
         public bool Failed => !Succeeded;
@@ -25,17 +25,17 @@ namespace Wabbajack
         }
 
         bool IErrorResponse.Succeeded => Succeeded;
-        Exception IErrorResponse.Exception => Exception;
+        Exception? IErrorResponse.Exception => Exception;
 
         private GetResponse(
             bool succeeded,
-            T val = default(T),
+            T val = default,
-            string reason = null,
+            string? reason = null,
-            Exception ex = null)
+            Exception? ex = null)
         {
             Value = val;
             Succeeded = succeeded;
-            _reason = reason;
+            _reason = reason ?? string.Empty;
             Exception = ex;
         }
 
@@ -45,7 +45,7 @@ namespace Wabbajack
                 && Equals(Value, other.Value);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (!(obj is GetResponse<T> rhs)) return false;
             return Equals(rhs);
@@ -53,8 +53,10 @@ namespace Wabbajack
 
         public override int GetHashCode()
         {
-            return HashHelper.GetHashCode(Value)
+            System.HashCode hash = new HashCode();
-                .CombineHashCode(Succeeded.GetHashCode());
+            hash.Add(Value);
+            hash.Add(Succeeded);
+            return hash.ToHashCode();
         }
 
         public override string ToString()
@@ -124,7 +126,7 @@ namespace Wabbajack
             return new GetResponse<T>(false, val);
         }
 
-        public static GetResponse<T> Create(bool successful, T val = default(T), string reason = null)
+        public static GetResponse<T> Create(bool successful, T val = default(T), string? reason = null)
         {
             return new GetResponse<T>(successful, val, reason);
         }

Wabbajack.Common/Extensions/DictionaryExt.cs

@@ -6,17 +6,37 @@ namespace Wabbajack
     public static class DictionaryExt
     {
         public static V TryCreate<K, V>(this IDictionary<K, V> dict, K key)
+            where K : notnull
             where V : new()
         {
             return dict.TryCreate(key, () => new V());
         }
 
         public static V TryCreate<K, V>(this IDictionary<K, V> dict, K key, Func<V> create)
+            where K : notnull
         {
             if (dict.TryGetValue(key, out var val)) return val;
             var ret = create();
             dict[key] = ret;
             return ret;
         }
+
+        public static void Add<K, V>(this IDictionary<K, V> dict, IEnumerable<KeyValuePair<K, V>> vals)
+            where K : notnull
+        {
+            foreach (var val in vals)
+            {
+                dict.Add(val);
+            }
+        }
+
+        public static void Set<K, V>(this IDictionary<K, V> dict, IEnumerable<KeyValuePair<K, V>> vals)
+            where K : notnull
+        {
+            foreach (var val in vals)
+            {
+                dict[val.Key] = val.Value;
+            }
+        }
     }
 }

Wabbajack.Common/Extensions/EnumExt.cs

@@ -21,8 +21,8 @@ namespace Wabbajack.Common
                 throw new ArgumentException("T must be an Enum");
             }
 
-            var attributes = (DescriptionAttribute[])val.GetType().GetField(val.ToString()).GetCustomAttributes(typeof(DescriptionAttribute), false);
+            var attributes = (DescriptionAttribute[])val.GetType().GetField(val.ToString()!)!.GetCustomAttributes(typeof(DescriptionAttribute), false);
-            return attributes.Length > 0 ? attributes[0].Description : val.ToString();
+            return attributes.Length > 0 ? attributes[0].Description : val.ToString()!;
         }
     }
 }

Wabbajack.Common/Extensions/EnumerableExt.cs

@@ -11,9 +11,6 @@ namespace Wabbajack
 
         public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> source, Random rng)
         {
-            if (source == null) throw new ArgumentNullException("source");
-            if (rng == null) throw new ArgumentNullException("rng");
-
             return source.ShuffleIterator(rng);
         }
 
@@ -30,5 +27,11 @@ namespace Wabbajack
             }
         }
         #endregion
+
+        public static IEnumerable<T> Cons<T>(this IEnumerable<T> coll, T next)
+        {
+            yield return next;
+            foreach (var itm in coll) yield return itm;
+        }
     }
 }

Wabbajack.Common/Extensions/HashHelper.cs

@@ -1,133 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-/*
- * Taken from: http://stackoverflow.com/questions/263400/what-is-the-best-algorithm-for-an-overridden-system-object-gethashcode
- */
-namespace Wabbajack
-{
-    public static class HashHelper
-    {
-        public static int GetHashCode<T1, T2>(T1 arg1, T2 arg2)
-        {
-            unchecked
-            {
-                return 31 * (arg1 == null ? 0 : arg1.GetHashCode())
-                    + (arg2 == null ? 0 : arg2.GetHashCode());
-            }
-        }
-
-        public static int GetHashCode<T1, T2, T3>(T1 arg1, T2 arg2, T3 arg3)
-        {
-            unchecked
-            {
-                int hash = (arg1 == null ? 0 : arg1.GetHashCode());
-                hash = 31 * hash + (arg2 == null ? 0 : arg2.GetHashCode());
-                return 31 * hash + (arg3 == null ? 0 : arg3.GetHashCode());
-            }
-        }
-
-        public static int GetHashCode<T1, T2, T3, T4>(T1 arg1, T2 arg2, T3 arg3, T4 arg4)
-        {
-            unchecked
-            {
-                int hash = (arg1 == null ? 0 : arg1.GetHashCode());
-                hash = 31 * hash + (arg2 == null ? 0 : arg2.GetHashCode());
-                hash = 31 * hash + (arg3 == null ? 0 : arg3.GetHashCode());
-                return 31 * hash + (arg4 == null ? 0 : arg4.GetHashCode());
-            }
-        }
-
-        public static int GetHashCode<T>(params T[] list)
-        {
-            unchecked
-            {
-                int hash = 0;
-                if (list == null) return hash;
-                for (int i = 0; i < list.Length; i++)
-                {
-                    hash = 31 * hash + GetHashCode(list[i]);
-                }
-                return hash;
-            }
-        }
-
-        public static int GetHashCode<T>(ReadOnlySpan<T> span)
-        {
-            unchecked
-            {
-                int hash = 0;
-                if (span == null) return hash;
-                for (int i = 0; i < span.Length; i++)
-                {
-                    hash = 31 * hash + GetHashCode(span[i]);
-                }
-                return hash;
-            }
-        }
-
-        public static int GetHashCode<T>(T t)
-        {
-            unchecked
-            {
-                return (t == null ? 0 : t.GetHashCode());
-            }
-        }
-
-        public static int GetHashCode<T>(IEnumerable<T> list)
-        {
-            unchecked
-            {
-                int hash = 0;
-                foreach (var item in list)
-                {
-                    hash = 31 * hash + (item == null ? 0 : item.GetHashCode());
-                }
-                return hash;
-            }
-        }
-
-        /// <summary>
-        /// Gets a hashcode for a collection for that the order of items 
-        /// does not matter.
-        /// So {1, 2, 3} and {3, 2, 1} will get same hash code.
-        /// </summary>
-        public static int GetHashCode_OrderBlind<T>(
-            IEnumerable<T> list)
-        {
-            unchecked
-            {
-                int hash = 0;
-                int count = 0;
-                foreach (var item in list)
-                {
-                    hash += (item == null ? 0 : item.GetHashCode());
-                    count++;
-                }
-                return 31 * hash + count.GetHashCode();
-            }
-        }
-
-        /// <summary>
-        /// Alternative way to get a hashcode is to use a fluent 
-        /// interface like this:<br />
-        /// return 0.CombineHashCode(field1).CombineHashCode(field2).
-        ///     CombineHashCode(field3);
-        /// </summary>
-        public static int CombineHashCode<T>(this int hashCode, T arg)
-        {
-            unchecked
-            {
-                return CombineHashCode(hashCode, (arg == null ? 0 : arg.GetHashCode()));
-            }
-        }
-
-        public static int CombineHashCode(this int hashCode, int rhsHash)
-        {
-            unchecked
-            {
-                return 31 * hashCode + rhsHash;
-            }
-        }
-    }
-}

Wabbajack.Common/Extensions/RxExt.cs

@@ -16,10 +16,12 @@ namespace Wabbajack
         /// <typeparam name="T"></typeparam>
         /// <param name="source"></param>
         /// <returns>Source events that are not null</returns>
-        public static IObservable<T> NotNull<T>(this IObservable<T> source)
+        public static IObservable<T> NotNull<T>(this IObservable<T?> source)
             where T : class
         {
-            return source.Where(u => u != null);
+            return source
+                .Where(u => u != null)
+                .Select(u => u!);
         }
 
         /// <summary>
@@ -88,9 +90,9 @@ namespace Wabbajack
         /// Inspiration:
         /// http://reactivex.io/documentation/operators/debounce.html
         /// https://stackoverflow.com/questions/20034476/how-can-i-use-reactive-extensions-to-throttle-events-using-a-max-window-size
-        public static IObservable<T> Debounce<T>(this IObservable<T> source, TimeSpan interval, IScheduler scheduler = null)
+        public static IObservable<T> Debounce<T>(this IObservable<T> source, TimeSpan interval, IScheduler? scheduler = null)
         {
-            scheduler = scheduler ?? Scheduler.Default;
+            scheduler ??= Scheduler.Default;
             return Observable.Create<T>(o =>
             {
                 var hasValue = false;
@@ -218,8 +220,8 @@ namespace Wabbajack
                     .StartWith(false));
         }
 
-        public static IObservable<T> DisposeOld<T>(this IObservable<T> source)
+        public static IObservable<T?> DisposeOld<T>(this IObservable<T?> source)
-            where T : IDisposable
+            where T : class, IDisposable
         {
             return source
                 .StartWith(default(T))

Wabbajack.Common/Extensions/TaskExt.cs

@@ -5,7 +5,7 @@ namespace Wabbajack
 {
     public static class TaskExt
     {
-        public static async void FireAndForget(this Task task, Action<Exception> onException = null)
+        public static async void FireAndForget(this Task task, Action<Exception>? onException = null)
         {
             try
             {

Wabbajack.Common/GameMetaData.cs

@@ -58,45 +58,46 @@ namespace Wabbajack.Common
     public class GameMetaData
     {
         public ModManager SupportedModManager { get; internal set; }
-        public string MO2ArchiveName { get; internal set; }
+        public string? MO2ArchiveName { get; internal set; }
         public Game Game { get; internal set; }
-        public string NexusName { get; internal set; }
+        public string? NexusName { get; internal set; }
         // Nexus DB id for the game, used in some specific situations
         public long NexusGameId { get; internal set; }
-        public string MO2Name { get; internal set; }
+        public string? MO2Name { get; internal set; }
 
         public string HumanFriendlyGameName => Game.GetDescription();
         
-        public string GameLocationRegistryKey { get; internal set; }
+        public string? GameLocationRegistryKey { get; internal set; }
         // to get steam ids: https://steamdb.info
-        public List<int> SteamIDs { get; internal set; }
+        public List<int>? SteamIDs { get; internal set; }
         // to get gog ids: https://www.gogdb.org
-        public List<int> GOGIDs { get; internal set; }
+        public List<int>? GOGIDs { get; internal set; }
         // these are additional folders when a game installs mods outside the game folder
-        public List<string> AdditionalFolders { get; internal set; }
+        public List<string>? AdditionalFolders { get; internal set; }
         // file to check if the game is present, useful when steamIds and gogIds dont help
-        public List<string> RequiredFiles { get; internal set; }
+        public List<string>? RequiredFiles { get; internal set; }
         public bool Disabled { get; internal set; }
 
         // Games that this game are commonly confused with, for example Skyrim SE vs Skyrim LE
-        public Game[] CommonlyConfusedWith { get; set; }
+        public Game[] CommonlyConfusedWith { get; set; } = Array.Empty<Game>();
         
         public string InstalledVersion
         {
             get
             {
-                if (GameLocation() == null)
+                AbsolutePath? gameLoc = GameLocation();
+                if (gameLoc == null)
                     throw new GameNotInstalledException(this);
                 if (MainExecutable == null)
                     throw new NotImplementedException();
 
-                return FileVersionInfo.GetVersionInfo((string)GameLocation()?.Combine(MainExecutable)).ProductVersion;
+                return FileVersionInfo.GetVersionInfo((string)gameLoc.Value.Combine(MainExecutable)).ProductVersion;
             }
         }
 
         public bool IsInstalled => GameLocation() != null;
 
-        public string MainExecutable { get; internal set; }
+        public string? MainExecutable { get; internal set; }
 
         public AbsolutePath? GameLocation()
         {
@@ -114,14 +115,14 @@ namespace Wabbajack.Common
     public static class EnumExtensions
     {
         public static string GetDescription<T>(this T enumerationValue)
-            where T : struct
+            where T : Enum
         {
             var type = enumerationValue.GetType();
             if(!type.IsEnum)
             {
                 throw new ArgumentException($"{nameof(enumerationValue)} must be of Enum type", nameof(enumerationValue));
             }
-            var memberInfo = type.GetMember(enumerationValue.ToString());
+            var memberInfo = type.GetMember(enumerationValue.ToString()!);
             if(memberInfo.Length > 0)
             {
                 var attrs = memberInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
@@ -131,7 +132,7 @@ namespace Wabbajack.Common
                     return ((DescriptionAttribute)attrs[0]).Description;
                 }
             }
-            return enumerationValue.ToString();
+            return enumerationValue.ToString()!;
         }
     }
 
@@ -158,12 +159,11 @@ namespace Wabbajack.Common
         /// Tries to parse game data from an arbitrary string. Tries first via parsing as a game Enum, then by Nexus name,
         /// <param nambe="someName"></param>
         /// <returns></returns>
-        public static GameMetaData GetByFuzzyName(string someName)
+        public static GameMetaData? GetByFuzzyName(string someName)
         {
+            if (Enum.TryParse(typeof(Game), someName, true, out var metadata)) return ((Game)metadata!).MetaData();
 
-            if (Enum.TryParse(typeof(Game), someName, true, out var metadata)) return ((Game)metadata).MetaData();
+            GameMetaData? result = null;
-
-            GameMetaData result = null;
 
             result = GetByNexusName(someName);
             if (result != null) return result;

Wabbajack.Common/Hash.cs

@@ -1,5 +1,4 @@
-#nullable enable
+using System;
-using System;
 using System.Collections.Generic;
 using System.Data.HashFunction.xxHash;
 using System.IO;

Wabbajack.Common/Json.cs

@@ -52,7 +52,7 @@ namespace Wabbajack.Common
                 new JsonSerializerSettings
                 {
                     TypeNameHandling = handling, TypeNameAssemblyFormatHandling = format, Converters = Converters
-                });
+                })!;
         }
 
         public static T FromJSONString<T>(this string data,
@@ -63,7 +63,7 @@ namespace Wabbajack.Common
                 new JsonSerializerSettings
                 {
                     TypeNameHandling = handling, TypeNameAssemblyFormatHandling = format, Converters = Converters
-                });
+                })!;
         }
 
         public static T FromJSON<T>(this Stream data)
@@ -72,7 +72,7 @@ namespace Wabbajack.Common
             try
             {
                 return JsonConvert.DeserializeObject<T>(s,
-                    new JsonSerializerSettings {TypeNameHandling = TypeNameHandling.Auto, Converters = Converters});
+                    new JsonSerializerSettings {TypeNameHandling = TypeNameHandling.Auto, Converters = Converters})!;
             }
             catch (JsonSerializationException)
             {
@@ -95,7 +95,7 @@ namespace Wabbajack.Common
             public override Hash ReadJson(JsonReader reader, Type objectType, Hash existingValue, bool hasExistingValue,
                 JsonSerializer serializer)
             {
-                return Hash.FromBase64((string)reader.Value);
+                return Hash.FromBase64((string)reader.Value!);
             }
         }
 
@@ -110,7 +110,7 @@ namespace Wabbajack.Common
                 bool hasExistingValue,
                 JsonSerializer serializer)
             {
-                return (RelativePath)(string)reader.Value;
+                return (RelativePath)(string)reader.Value!;
             }
         }
 
@@ -125,7 +125,7 @@ namespace Wabbajack.Common
                 bool hasExistingValue,
                 JsonSerializer serializer)
             {
-                return (AbsolutePath)(string)reader.Value;
+                return (AbsolutePath)(string)reader.Value!;
             }
         }
 
@@ -133,7 +133,7 @@ namespace Wabbajack.Common
         {
             public override Percent ReadJson(JsonReader reader, Type objectType, Percent existingValue, bool hasExistingValue, JsonSerializer serializer)
             {
-                double d = (double)reader.Value;
+                double d = (double)reader.Value!;
                 return Percent.FactoryPutInRange(d);
             }
 
@@ -162,13 +162,13 @@ namespace Wabbajack.Common
                     throw new JsonException("Invalid JSON state while reading Hash Relative Path");
                 reader.Read();
 
-                var hash = Hash.FromBase64((string)reader.Value);
+                var hash = Hash.FromBase64((string)reader.Value!);
                 var paths = new List<RelativePath>();
 
                 reader.Read();
                 while (reader.TokenType != JsonToken.EndArray)
                 {
-                    paths.Add((RelativePath)(string)reader.Value);
+                    paths.Add((RelativePath)(string)reader.Value!);
                     reader.Read();
                 }
 
@@ -195,13 +195,13 @@ namespace Wabbajack.Common
                     throw new JsonException("Invalid JSON state while reading Hash Relative Path");
                 reader.Read();
 
-                var abs = (AbsolutePath)(string)reader.Value;
+                var abs = (AbsolutePath)(string)reader.Value!;
                 var paths = new List<RelativePath>();
 
                 reader.Read();
                 while (reader.TokenType != JsonToken.EndArray)
                 {
-                    paths.Add((RelativePath)(string)reader.Value);
+                    paths.Add((RelativePath)(string)reader.Value!);
                     reader.Read();
                 }
 
@@ -228,7 +228,13 @@ namespace Wabbajack.Common
                     return (Game)i;
                 }
 
-                return GameRegistry.GetByFuzzyName(str).Game;
+                GameMetaData? game = GameRegistry.GetByFuzzyName(str);
+                if (game == null)
+                {
+                    throw new ArgumentException($"Could not convert {str} to a Game type.");
+                }
+
+                return game.Game;
             }
         }
     }

Wabbajack.Common/KnownFolders/KnownFolder.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Runtime.InteropServices;
 using System.Security.Principal;
+#nullable disable
 
 namespace Wabbajack.Common.IO
 {

Wabbajack.Common/KnownFolders/KnownFolderType.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Reflection;
+#nullable disable
 
 namespace Wabbajack.Common.IO
 {

Wabbajack.Common/KnownFolders/KnownFolders.cs

@@ -1,5 +1,6 @@
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+#nullable disable
 
 namespace Wabbajack.Common.IO
 {

Wabbajack.Common/MessagePack.cs

@@ -11,8 +11,8 @@ namespace Wabbajack.Common
 {
     public partial class Utils
     {
-        private static MessagePackSerializerOptions _messagePackOptions;
+        private static MessagePackSerializerOptions? _messagePackOptions;
-        private static IFormatterResolver _resolver;
+        private static IFormatterResolver? _resolver;
 
         private static void MessagePackInit()
         {

Wabbajack.Common/ModListAssociationManager.cs

@@ -39,7 +39,7 @@ namespace Wabbajack.Common
             var tempKey = progIDKey?.OpenSubKey("shell\\open\\command");
             if (progIDKey == null || tempKey == null) return true;
             var value = tempKey.GetValue("");
-            return value == null || !value.ToString().Equals($"\"{execPath}\" -i=\"%1\"");
+            return value == null || !string.Equals(value.ToString(), $"\"{execPath}\" -i=\"%1\"");
         }
 
         public static bool IsAssociated()

Wabbajack.Common/Paths.cs

@@ -33,7 +33,7 @@ namespace Wabbajack.Common
             return string.Equals(_path, other._path, StringComparison.InvariantCultureIgnoreCase);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is AbsolutePath other && Equals(other);
         }
@@ -42,7 +42,7 @@ namespace Wabbajack.Common
 
         public override int GetHashCode()
         {
-            return _path?.GetHashCode(StringComparison.InvariantCultureIgnoreCase) ?? 0;
+            return _path.GetHashCode(StringComparison.InvariantCultureIgnoreCase);
         }
 
         public override string ToString()
@@ -50,11 +50,12 @@ namespace Wabbajack.Common
             return _path;
         }
 
-        private readonly string _path;
+        private readonly string _nullable_path;
+        private string _path => _nullable_path ?? string.Empty;
 
         public AbsolutePath(string path, bool skipValidation = false)
         {
-            _path = path.Replace("/", "\\").TrimEnd('\\');
+            _nullable_path = path.Replace("/", "\\").TrimEnd('\\');
             if (!skipValidation)
             {
                 ValidateAbsolutePath();
@@ -63,7 +64,7 @@ namespace Wabbajack.Common
 
         public AbsolutePath(AbsolutePath path)
         {
-            _path = path._path;
+            _nullable_path = path._path;
         }
 
         private void ValidateAbsolutePath()
@@ -150,7 +151,8 @@ namespace Wabbajack.Common
                 var location = Assembly.GetEntryAssembly()?.Location ?? null;
                 if (location == null)
                     location = Assembly.GetExecutingAssembly().Location ?? null;
-
+                if (location == null)
+                    throw new ArgumentException("Could not find entry point.");
                 return ((AbsolutePath)location).Parent;
             }
         } 
@@ -264,7 +266,7 @@ namespace Wabbajack.Common
 
         public AbsolutePath Combine(params RelativePath[] paths)
         {
-            return new AbsolutePath(Path.Combine(paths.Select(s => (string)s).Where(s => s != null).Cons(_path).ToArray()));
+            return new AbsolutePath(Path.Combine(paths.Select(s => (string)s).Cons(_path).ToArray()));
         }
 
         public AbsolutePath Combine(params string[] paths)
@@ -371,23 +373,24 @@ namespace Wabbajack.Common
 
     public struct RelativePath : IPath, IEquatable<RelativePath>, IComparable<RelativePath>
     {
-        private readonly string _path;
+        private readonly string? _nullable_path;
+        private string _path => _nullable_path ?? string.Empty;
 
         public RelativePath(string path)
         {
             if (string.IsNullOrWhiteSpace(path))
             {
-                _path = null;
+                _nullable_path = null;
                 return;
             }
             var trimmed = path.Replace("/", "\\").Trim('\\');
             if (string.IsNullOrEmpty(trimmed))
             {
-                _path = null;
+                _nullable_path = null;
                 return;
             }
 
-            _path = trimmed;
+            _nullable_path = trimmed;
             Validate();
         }
 
@@ -400,7 +403,7 @@ namespace Wabbajack.Common
 
         public override int GetHashCode()
         {
-            return _path?.GetHashCode(StringComparison.InvariantCultureIgnoreCase) ?? 0;
+            return _path.GetHashCode(StringComparison.InvariantCultureIgnoreCase);
         }
 
         public static RelativePath RandomFileName()
@@ -418,7 +421,7 @@ namespace Wabbajack.Common
 
         public AbsolutePath RelativeTo(AbsolutePath abs)
         {
-            return _path == null ? abs : new AbsolutePath(Path.Combine((string)abs, _path));
+            return new AbsolutePath(Path.Combine((string)abs, _path));
         }
 
         public AbsolutePath RelativeToEntryPoint()
@@ -470,7 +473,7 @@ namespace Wabbajack.Common
             return string.Equals(_path, other._path, StringComparison.InvariantCultureIgnoreCase);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is RelativePath other && Equals(other);
         }
@@ -586,7 +589,7 @@ namespace Wabbajack.Common
             return string.Equals(_extension, other._extension, StringComparison.InvariantCultureIgnoreCase);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is Extension other && Equals(other);
         }
@@ -603,23 +606,24 @@ namespace Wabbajack.Common
 
         #endregion
 
-        private readonly string _extension;
+        private readonly string? _nullable_extension;
+        private string _extension => _nullable_extension ?? string.Empty;
 
         public Extension(string extension)
         {
             if (string.IsNullOrWhiteSpace(extension))
             {
-                _extension = None._extension;
+                _nullable_extension = None._extension;
                 return;
             }
 
-            _extension = string.Intern(extension);
+            _nullable_extension = string.Intern(extension);
             Validate();
         }
 
         private Extension(string extension, bool validate)
         {
-            _extension = string.Intern(extension);
+            _nullable_extension = string.Intern(extension);
             if (validate)
             {
                 Validate();
@@ -628,7 +632,7 @@ namespace Wabbajack.Common
 
         public Extension(Extension other)
         {
-            _extension = other._extension;
+            _nullable_extension = other._extension;
         }
 
         private void Validate()
@@ -652,16 +656,6 @@ namespace Wabbajack.Common
         public static bool operator ==(Extension a, Extension b)
         {
             // Super fast comparison because extensions are interned
-            if ((object)a == null && (object)b == null)
-            {
-                return true;
-            }
-
-            if ((object)a == null || (object)b == null)
-            {
-                return false;
-            }
-
             return ReferenceEquals(a._extension, b._extension);
         }
 
@@ -726,7 +720,7 @@ namespace Wabbajack.Common
             return this == other;
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is HashRelativePath other && Equals(other);
         }
@@ -772,7 +766,6 @@ namespace Wabbajack.Common
 
         public static bool operator ==(FullPath a, FullPath b)
         {
-            if (a.Paths == null || b.Paths == null) return false;
             if (a.Base != b.Base || a.Paths.Length != b.Paths.Length)
             {
                 return false;
@@ -799,7 +792,7 @@ namespace Wabbajack.Common
             return this == other;
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is FullPath other && Equals(other);
         }

Wabbajack.Common/ProcessHelper.cs

@@ -16,8 +16,8 @@ namespace Wabbajack.Common
             Error,
         }
 
-        public string Path { get; set; }
+        public string Path { get; set; } = string.Empty;
-        public IEnumerable<object> Arguments { get; set; }
+        public IEnumerable<object> Arguments { get; set; } = Enumerable.Empty<object>();
 
         public bool LogError { get; set; } = true;
         

Wabbajack.Common/StatusFeed/Errors/FileExtractionError.cs

@@ -10,8 +10,8 @@ namespace Wabbajack.Common.StatusFeed.Errors
     {
         private string _filename;
         private string _destination;
-        public override string ShortDescription { get; }
+        public override string ShortDescription { get; } = string.Empty;
-        public override string ExtendedDescription { get; }
+        public override string ExtendedDescription { get; } = string.Empty;
 
         public FileExtractionError(string filename, string destination)
         {

Wabbajack.Common/StatusFeed/Errors/GenericException.cs

@@ -8,19 +8,19 @@ namespace Wabbajack.Common.StatusFeed.Errors
 {
     public class GenericException : IException
     {
-        public string ExtraMessage { get; }
+        public string ExtraMessage { get; } = string.Empty;
 
         public DateTime Timestamp { get; } = DateTime.Now;
 
-        public string ShortDescription => ExtraMessage == null ? Exception?.Message : $"{ExtraMessage} - {Exception?.Message}";
+        public string ShortDescription => string.IsNullOrWhiteSpace(ExtraMessage) ? Exception?.Message ?? string.Empty : $"{ExtraMessage} - {Exception?.Message}";
 
-        public string ExtendedDescription => ExtraMessage == null ? Exception?.ToString() : $"{ExtraMessage} - {Exception?.ToString()}";
+        public string ExtendedDescription => string.IsNullOrWhiteSpace(ExtraMessage) ? Exception?.ToString() ?? string.Empty : $"{ExtraMessage} - {Exception?.ToString()}";
 
         public Exception Exception { get; }
 
-        public GenericException(Exception exception, string extraMessage = null)
+        public GenericException(Exception exception, string? extraMessage = null)
         {
-            ExtraMessage = extraMessage;
+            ExtraMessage = extraMessage ?? string.Empty;
             Exception = exception;
         }
     }

Wabbajack.Common/StatusFeed/GenericInfo.cs

@@ -12,10 +12,10 @@ namespace Wabbajack.Common.StatusFeed
         private readonly string _extendedDescription;
         public override string ExtendedDescription => _extendedDescription ?? ShortDescription;
 
-        public GenericInfo(string short_description, string long_description = null)
+        public GenericInfo(string short_description, string? long_description = null)
         {
             ShortDescription = short_description;
-            _extendedDescription = long_description;
+            _extendedDescription = long_description ?? string.Empty;
         }
 
         public override string ToString()

Wabbajack.Common/StatusFileStream.cs

@@ -6,9 +6,9 @@ namespace Wabbajack.Common
     {
         private string _message;
         private Stream _inner;
-        private WorkQueue _queue;
+        private WorkQueue? _queue;
 
-        public StatusFileStream(Stream fs, string message, WorkQueue queue = null)
+        public StatusFileStream(Stream fs, string message, WorkQueue? queue = null)
         {
             _queue = queue;
             _inner = fs;

Wabbajack.Common/StoreHandlers/GOGHandler.cs

@@ -10,21 +10,17 @@ namespace Wabbajack.Common.StoreHandlers
     public class GOGGame : AStoreGame
     {
         public override Game Game { get; internal set; }
-        public override string Name { get; internal set; }
-        public override AbsolutePath Path { get; internal set; }
-        public override int ID { get; internal set; }
         public override StoreType Type { get; internal set; } = StoreType.GOG;
     }
 
     public class GOGHandler : AStoreHandler
     {
-        public override List<AStoreGame> Games { get; set; }
         public override StoreType Type { get; internal set; }
 
         private const string GOGRegKey = @"Software\GOG.com\Games";
         private const string GOG64RegKey = @"Software\WOW6432Node\GOG.com\Games";
 
-        private RegistryKey GOGKey { get; set; }
+        private RegistryKey? GOGKey { get; set; }
 
         public override bool Init()
         {
@@ -56,9 +52,11 @@ namespace Wabbajack.Common.StoreHandlers
 
         public override bool LoadAllGames()
         {
-            if(Games == null)
+            if (GOGKey == null)
-                Games = new List<AStoreGame>();
+            {
-
+                Utils.Error("GOGHandler could not read from registry!");
+                return false;
+            }
             try
             {
                 string[] keys = GOGKey.GetSubKeyNames();
@@ -86,7 +84,7 @@ namespace Wabbajack.Common.StoreHandlers
                         return;
                     }
 
-                    var gameName = gameNameValue.ToString();
+                    var gameName = gameNameValue.ToString() ?? string.Empty;
 
                     var pathValue = subKey.GetValue("PATH");
                     if (pathValue == null)
@@ -95,7 +93,7 @@ namespace Wabbajack.Common.StoreHandlers
                         return;
                     }
 
-                    var path = pathValue.ToString();
+                    var path = pathValue.ToString() ?? string.Empty;
 
                     var game = new GOGGame
                     {

Wabbajack.Common/StoreHandlers/SteamHandler.cs

@@ -11,33 +11,29 @@ namespace Wabbajack.Common.StoreHandlers
     public class SteamGame : AStoreGame
     {
         public override Game Game { get; internal set; }
-        public override string Name { get; internal set; }
-        public override AbsolutePath Path { get; internal set; }
-        public override int ID { get; internal set; }
         public override StoreType Type { get; internal set; } = StoreType.STEAM;
 
-        public string Universe;
+        public string Universe = string.Empty;
 
-        public List<SteamWorkshopItem> WorkshopItems;
+        public readonly List<SteamWorkshopItem> WorkshopItems = new List<SteamWorkshopItem>();
-        public int WorkshopItemsSize;
+        public int WorkshopItemsSizeOnDisk;
     }
 
     public class SteamWorkshopItem
     {
-        public SteamGame Game;
+        public SteamGame? Game;
         public int ItemID;
         public int Size;
     }
 
     public class SteamHandler : AStoreHandler
     {
-        public override List<AStoreGame> Games { get; set; }
         public override StoreType Type { get; internal set; } = StoreType.STEAM;
 
         private const string SteamRegKey = @"Software\Valve\Steam";
 
-        public string SteamPath { get; set; }
+        public string SteamPath { get; set; } = string.Empty;
-        private List<string> SteamUniverses { get; set; }
+        private List<string>? SteamUniverses { get; set; }
 
         private string SteamConfig => Path.Combine(SteamPath, "config", "config.vdf");
 
@@ -54,7 +50,7 @@ namespace Wabbajack.Common.StoreHandlers
                     return false;
                 }
 
-                SteamPath = steamPathKey.ToString();
+                SteamPath = steamPathKey.ToString() ?? string.Empty;
                 if (string.IsNullOrWhiteSpace(SteamPath))
                 {
                     Utils.Error(new StoreException("Path to the Steam Directory from registry is Null or Empty!"));
@@ -86,9 +82,9 @@ namespace Wabbajack.Common.StoreHandlers
             return false;
         }
 
-        private void LoadUniverses()
+        private List<string> LoadUniverses()
         {
-            SteamUniverses = new List<string>();
+            var ret = new List<string>();
 
             File.ReadAllLines(SteamConfig).Do(l =>
             {
@@ -101,21 +97,23 @@ namespace Wabbajack.Common.StoreHandlers
                     return;
                 }
 
-                SteamUniverses.Add(s);
+                ret.Add(s);
                 Utils.Log($"Steam Library found at {s}");
             });
 
-            Utils.Log($"Total number of Steam Libraries found: {SteamUniverses.Count}");
+            Utils.Log($"Total number of Steam Libraries found: {ret.Count}");
 
             // Default path in the Steam folder isn't in the configs
-            if(Directory.Exists(Path.Combine(SteamPath, "steamapps")))
+            if (Directory.Exists(Path.Combine(SteamPath, "steamapps")))
-                SteamUniverses.Add(Path.Combine(SteamPath, "steamapps"));
+                ret.Add(Path.Combine(SteamPath, "steamapps"));
+
+            return ret;
         }
 
         public override bool LoadAllGames()
         {
-            if(SteamUniverses == null)
+            if (SteamUniverses == null)
-                LoadUniverses();
+                SteamUniverses = LoadUniverses();
 
             if (SteamUniverses.Count == 0)
             {
@@ -123,9 +121,6 @@ namespace Wabbajack.Common.StoreHandlers
                 return false;
             }
 
-            if(Games == null)
-                Games = new List<AStoreGame>();
-
             SteamUniverses.Do(u =>
             {
                 Utils.Log($"Searching for Steam Games in {u}");
@@ -188,9 +183,6 @@ namespace Wabbajack.Common.StoreHandlers
 
         private static void LoadWorkshopItems(SteamGame game)
         {
-            if(game.WorkshopItems == null)
-                game.WorkshopItems = new List<SteamWorkshopItem>();
-
             var workshop = Path.Combine(game.Universe, "workshop");
             if (!Directory.Exists(workshop))
                 return;
@@ -210,13 +202,13 @@ namespace Wabbajack.Common.StoreHandlers
                 var bracketStart = 0;
                 var bracketEnd = 0;
 
-                var currentItem = new SteamWorkshopItem();
+                SteamWorkshopItem? currentItem = new SteamWorkshopItem();
 
                 lines.Do(l =>
                 {
                     if (end)
                         return;
-                    if(currentItem == null)
+                    if (currentItem == null)
                         currentItem = new SteamWorkshopItem();
 
                     var currentLine = lines.IndexOf(l);
@@ -239,7 +231,7 @@ namespace Wabbajack.Common.StoreHandlers
                         if (!int.TryParse(GetVdfValue(l), out var sizeOnDisk))
                             return;
 
-                        game.WorkshopItemsSize += sizeOnDisk;
+                        game.WorkshopItemsSizeOnDisk += sizeOnDisk;
                     }
 
                     if (l.ContainsCaseInsensitive("\"WorkshopItemsInstalled\""))

Wabbajack.Common/StoreHandlers/StoreHandler.cs

@@ -61,15 +61,15 @@ namespace Wabbajack.Common.StoreHandlers
     public abstract class AStoreGame
     {
         public abstract Game Game { get; internal set; }
-        public abstract string Name { get; internal set; }
+        public virtual string Name { get; internal set; } = string.Empty;
-        public abstract AbsolutePath Path { get; internal set; }
+        public virtual AbsolutePath Path { get; internal set; }
-        public abstract int ID { get; internal set; }
+        public virtual int ID { get; internal set; }
         public abstract StoreType Type { get; internal set; }
     }
 
     public abstract class AStoreHandler
     {
-        public abstract List<AStoreGame> Games { get; set; }
+        public List<AStoreGame> Games { get; } = new List<AStoreGame>();
 
         public abstract StoreType Type { get; internal set; }
 

Wabbajack.Common/Util/AsyncLock.cs

@@ -10,7 +10,7 @@ namespace Wabbajack.Common
 {
     public class AsyncLock
     {
-        private SemaphoreSlim _lock = new SemaphoreSlim(1, 1);
+        private readonly SemaphoreSlim _lock = new SemaphoreSlim(1, 1);
 
         public async Task<IDisposable> Wait()
         {

Wabbajack.Common/Util/DiskSlabAllocator.cs

@@ -43,9 +43,9 @@ namespace Wabbajack.Common
         public void Dispose()
         {
             _allocated.Do(s => s.Dispose());
-            _mmap?.Dispose();
+            _mmap.Dispose();
-            _fileStream?.Dispose();
+            _fileStream.Dispose();
-            _file?.Dispose();
+            _file.Dispose();
         }
     }
 }

Wabbajack.Common/Util/Percent.cs

@@ -142,7 +142,7 @@ namespace Wabbajack.Common
             return new Percent(percent, check: false);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (!(obj is Percent rhs)) return false;
             return Equals(rhs);
@@ -191,7 +191,7 @@ namespace Wabbajack.Common
             }
         }
 
-        public int CompareTo(object obj)
+        public int CompareTo(object? obj)
         {
             if (obj is Percent rhs)
             {

Wabbajack.Common/Util/TempFile.cs

@@ -6,7 +6,6 @@ using System.Text;
 using System.Threading.Tasks;
 using AlphaPath = Alphaleonis.Win32.Filesystem.Path;
 
-
 namespace Wabbajack.Common
 {
     public class TempFile : IDisposable

Wabbajack.Common/Utils.cs

@@ -3,6 +3,7 @@ using System.Collections;
 using System.Collections.Generic;
 using System.Data.HashFunction.xxHash;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using System.Net.Http;
@@ -132,12 +133,12 @@ namespace Wabbajack.Common
             Log(errMessage);
         }
 
-        public static void Error(Exception ex, string extraMessage = null)
+        public static void Error(Exception ex, string? extraMessage = null)
         {
             Log(new GenericException(ex, extraMessage));
         }
 
-        public static void ErrorThrow(Exception ex, string extraMessage = null)
+        public static void ErrorThrow(Exception ex, string? extraMessage = null)
         {
             Error(ex, extraMessage);
             throw ex;
@@ -231,29 +232,21 @@ namespace Wabbajack.Common
                 Status(status, Percent.FactoryPutInRange(totalRead, maxSize));
             }
         }
-        public static string xxHash(this byte[] data, bool nullOnIOError = false)
+        public static string xxHash(this byte[] data)
         {
-            try
+            var hash = new xxHashConfig();
+            hash.HashSizeInBits = 64;
+            hash.Seed = 0x42;
+            using (var fs = new MemoryStream(data))
             {
-                var hash = new xxHashConfig();
+                var config = new xxHashConfig();
-                hash.HashSizeInBits = 64;
+                config.HashSizeInBits = 64;
-                hash.Seed = 0x42;
+                using (var f = new StatusFileStream(fs, $"Hashing memory stream"))
-                using (var fs = new MemoryStream(data))
                 {
-                    var config = new xxHashConfig();
+                    var value = xxHashFactory.Instance.Create(config).ComputeHash(f);
-                    config.HashSizeInBits = 64;
+                    return value.AsBase64String();
-                    using (var f = new StatusFileStream(fs, $"Hashing memory stream"))
-                    {
-                        var value = xxHashFactory.Instance.Create(config).ComputeHash(f);
-                        return value.AsBase64String();
-                    }
                 }
             }
-            catch (IOException ex)
-            {
-                if (nullOnIOError) return null;
-                throw ex;
-            }
         }
 
         /// <summary>
@@ -673,7 +666,9 @@ namespace Wabbajack.Common
             return a[a.Length - 1];
         }
 
+        [return: MaybeNull]
         public static V GetOrDefault<K, V>(this IDictionary<K, V> dict, K key)
+            where K : notnull
         {
             if (dict.TryGetValue(key, out var v)) return v;
             return default;
@@ -776,7 +771,7 @@ namespace Wabbajack.Common
             }
         }
 
-        public static bool TryGetPatch(Hash foundHash, Hash fileHash, out byte[] ePatch)
+        public static bool TryGetPatch(Hash foundHash, Hash fileHash, [MaybeNullWhen(false)] out byte[] ePatch)
         {
             var patchName = Consts.PatchCacheFolder.Combine($"{foundHash.ToHex()}_{fileHash.ToHex()}.patch");
             if (patchName.Exists)
@@ -809,17 +804,6 @@ namespace Wabbajack.Common
 
         }
 
-        /*
-        public static void Warning(string s)
-        {
-            Log($"WARNING: {s}");
-        }*/
-
-        public static TV GetOrDefault<TK, TV>(this Dictionary<TK, TV> dict, TK key)
-        {
-            return dict.TryGetValue(key, out var result) ? result : default;
-        }
-
         public static IEnumerable<T> ButLast<T>(this IEnumerable<T> coll)
         {
             var lst = coll.ToList();
@@ -1097,7 +1081,7 @@ namespace Wabbajack.Common
         public class NexusErrorResponse
         {
             public int code;
-            public string message;
+            public string message = string.Empty;
         }
 
         [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]

Wabbajack.Common/Wabbajack.Common.csproj

@@ -4,7 +4,7 @@
         <TargetFramework>netcoreapp3.1</TargetFramework>
         <Platforms>x64</Platforms>
         <RuntimeIdentifier>win10-x64</RuntimeIdentifier>
-        
+        <Nullable>enable</Nullable>
     </PropertyGroup>
     <ItemGroup>
         <None Remove="7z.dll.gz" />

Wabbajack.Common/WorkQueue.cs

@@ -25,7 +25,7 @@ namespace Wabbajack.Common
 
         public static bool WorkerThread => AsyncLocalCurrentQueue.Value != null;
         public bool IsWorkerThread => WorkerThread;
-        internal static readonly AsyncLocal<WorkQueue> AsyncLocalCurrentQueue = new AsyncLocal<WorkQueue>();
+        internal static readonly AsyncLocal<WorkQueue?> AsyncLocalCurrentQueue = new AsyncLocal<WorkQueue?>();
 
         private readonly Subject<CPUStatus> _Status = new Subject<CPUStatus>();
         public IObservable<CPUStatus> Status => _Status;
@@ -194,7 +194,7 @@ namespace Wabbajack.Common
     public class CPUStatus
     {
         public Percent ProgressPercent { get; internal set; }
-        public string Msg { get; internal set; }
+        public string Msg { get; internal set; } = string.Empty;
         public int ID { get; internal set; }
         public bool IsWorking { get; internal set; }
     }