AbstractDownloadState.Download returns bool

There's sort of a theoretical disagreement, still.  Should a failed download throw an exception, or return false?  Users of this function still need to handle/prep for either/or.

Still, this is better than before, where some failures were being swallowed completely

Wabbajack.Lib/Downloaders/AbstractDownloadState.cs

@@ -60,15 +60,15 @@ namespace Wabbajack.Lib.Downloaders
         /// Downloads this file to the given destination location
         /// </summary>
         /// <param name="destination"></param>
-        public abstract Task Download(Archive a, string destination);
+        public abstract Task<bool> Download(Archive a, string destination);
 
-        public async Task Download(string destination)
+        public async Task<bool> Download(string destination)
         {
             var path = Path.GetDirectoryName(destination);
             if (!string.IsNullOrEmpty(path) && !Directory.Exists(path))
                 Directory.CreateDirectory(path);
             
-            await Download(new Archive {Name = Path.GetFileName(destination)}, destination);
+            return await Download(new Archive {Name = Path.GetFileName(destination)}, destination);
         }
 
         /// <summary>

Wabbajack.Lib/Downloaders/AbstractIPS4Downloader.cs

@@ -56,13 +56,14 @@ namespace Wabbajack.Lib.Downloaders
                 return true;
             }
 
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 var stream = await ResolveDownloadStream();
                 using (var file = File.OpenWrite(destination))
                 {
                     stream.CopyTo(file);
                 }
+                return true;
             }
 
             private async Task<Stream> ResolveDownloadStream()

Wabbajack.Lib/Downloaders/GameFileSourceDownloader.cs

@@ -62,7 +62,7 @@ namespace Wabbajack.Lib.Downloaders
                 return true;
             }
 
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 using(var src = File.OpenRead(SourcePath))
                 using (var dest = File.OpenWrite(destination))
@@ -70,6 +70,7 @@ namespace Wabbajack.Lib.Downloaders
                     var size = new FileInfo(SourcePath).Length;
                     src.CopyToWithStatus(size, dest, "Copying from Game folder");
                 }
+                return true;
             }
 
             public override async Task<bool> Verify(Archive a)

Wabbajack.Lib/Downloaders/GoogleDriveDownloader.cs

@@ -44,10 +44,10 @@ namespace Wabbajack.Lib.Downloaders
                 return whitelist.GoogleIDs.Contains(Id);
             }
 
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 var state = await ToHttpState();
-                await state.Download(a, destination);
+                return await state.Download(a, destination);
             }
 
             private async Task<HTTPDownloader.State> ToHttpState()

Wabbajack.Lib/Downloaders/HTTPDownloader.cs

@@ -70,7 +70,7 @@ namespace Wabbajack.Lib.Downloaders
                 return whitelist.AllowedPrefixes.Any(p => Url.StartsWith(p));
             }
 
-            public override Task Download(Archive a, string destination)
+            public override Task<bool> Download(Archive a, string destination)
             {
                 return DoDownload(a, destination, true);
             }

Wabbajack.Lib/Downloaders/MEGADownloader.cs

@@ -26,7 +26,7 @@ namespace Wabbajack.Lib.Downloaders
 
         public class State : HTTPDownloader.State
         {
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 var client = new MegaApiClient();
                 Utils.Status("Logging into MEGA (as anonymous)");
@@ -35,6 +35,7 @@ namespace Wabbajack.Lib.Downloaders
                 var node = client.GetNodeFromLink(fileLink);
                 Utils.Status($"Downloading MEGA file: {a.Name}");
                 client.DownloadFile(fileLink, destination);
+                return true;
             }
 
             public override async Task<bool> Verify(Archive a)

Wabbajack.Lib/Downloaders/ManualDownloader.cs

@@ -80,7 +80,7 @@ namespace Wabbajack.Lib.Downloaders
                 return true;
             }
 
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 var downloader = (ManualDownloader)GetDownloader();
                 var absPath = Path.Combine(downloader._downloadfolder.Path, a.Name);
@@ -109,6 +109,7 @@ namespace Wabbajack.Lib.Downloaders
                         downloader._watcher.EnableRaisingEvents = false;
                     }
                 }
+                return true;
             }
 
             public override async Task<bool> Verify(Archive a)

Wabbajack.Lib/Downloaders/MediaFireDownloader.cs

@@ -31,10 +31,10 @@ namespace Wabbajack.Lib.Downloaders
                 return whitelist.AllowedPrefixes.Any(p => Url.StartsWith(p));
             }
 
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 var result = await Resolve();
-                await result.Download(a, destination);
+                return await result.Download(a, destination);
             }
 
             public override async Task<bool> Verify(Archive a)

Wabbajack.Lib/Downloaders/ModDBDownloader.cs

@@ -46,23 +46,25 @@ namespace Wabbajack.Lib.Downloaders
                 return true;
             }
 
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 var urls = await GetDownloadUrls();
                 Utils.Log($"Found {urls.Length} ModDB mirrors for {a.Name}");
-                foreach (var (url, idx) in urls.Zip(Enumerable.Range(0, urls.Length), (s, i) => (s, i))) {
+                foreach (var (url, idx) in urls.Zip(Enumerable.Range(0, urls.Length), (s, i) => (s, i)))
+                {
                     try
                     {
                         await new HTTPDownloader.State {Url = url}.Download(a, destination);
-                        break;
+                        return true;
                     }
-                    catch (Exception ex)
+                    catch (Exception)
                     {
                         if (idx == urls.Length - 1)
                             throw;
                         Utils.Log($"Download from {url} failed, trying next mirror");
                     }
                 }
+                return false;
             }
 
             private async Task<string[]> GetDownloadUrls()

Wabbajack.Lib/Downloaders/NexusDownloader.cs

@@ -136,7 +136,7 @@ namespace Wabbajack.Lib.Downloaders
                 return true;
             }
 
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 string url;
                 try
@@ -147,16 +147,15 @@ namespace Wabbajack.Lib.Downloaders
                 catch (Exception ex)
                 {
                     Utils.Log($"{a.Name} - Error getting Nexus download URL - {ex.Message}");
-                    return;
+                    return false;
                 }
 
                 Utils.Log($"Downloading Nexus Archive - {a.Name} - {GameName} - {ModID} - {FileID}");
 
-                await new HTTPDownloader.State
+                return await new HTTPDownloader.State
                 {
                     Url = url
                 }.Download(a, destination);
-
             }
 
             public override async Task<bool> Verify(Archive a)

Wabbajack.Lib/Downloaders/SteamWorkshopDownloader.cs

@@ -49,7 +49,7 @@ namespace Wabbajack.Lib.Downloaders
                 return true;
             }
 
-            public override async Task Download(Archive a, string destination)
+            public override async Task<bool> Download(Archive a, string destination)
             {
                 var currentLib = Item.Game.Universe;
 
@@ -77,6 +77,8 @@ namespace Wabbajack.Lib.Downloaders
 
                     Thread.Sleep(1000);
                 }
+
+                return true;
             }
 
             public override async Task<bool> Verify(Archive a)