Fix overflow in PickupItem::amount and set persistence stack_size to i64

common/src/comp/inventory/item/mod.rs

@@ -1585,7 +1585,12 @@ impl PickupItem {
     pub fn next_merge_check_mut(&mut self) -> &mut ProgramTime { &mut self.next_merge_check }
 
     // Get the total amount of items in here
-    pub fn amount(&self) -> u32 { self.items.iter().map(Item::amount).sum() }
+    pub fn amount(&self) -> u32 {
+        self.items
+            .iter()
+            .map(Item::amount)
+            .fold(0, |total, amount| total.saturating_add(amount))
+    }
 
     /// Remove any debug items if this is a container, used before dropping an
     /// item from an inventory

server/src/persistence/character/conversions.rs

@@ -187,7 +187,7 @@ pub fn convert_items_to_database_items(
                     parent_container_item_id,
                     item_id,
                     stack_size: if item.is_stackable() {
-                        item.amount() as i32
+                        item.amount().into()
                     } else {
                         1
                     },

server/src/persistence/models.rs

@@ -11,7 +11,8 @@ pub struct Item {
     pub item_id: i64,
     pub parent_container_item_id: i64,
     pub item_definition_id: String,
-    pub stack_size: i32,
+    /// `u32::MAX` must fit inside this type
+    pub stack_size: i64,
     pub position: String,
     pub properties: String,
 }