Fix crash on custom item IDs from Forge servers (#1233)

* Fix unknown item id cause crashes for handling non-vanilla item (i.e. forge item)
* Add Unknown item type and use ItemType.Unknown for unknown items
Co-authored-by: ORelio <ORelio@users.noreply.github.com>

MinecraftClient/Inventory/ItemPalettes/ItemPalette.cs

@@ -15,17 +15,22 @@ namespace MinecraftClient.Inventory.ItemPalettes
             // Index reverse mappings for use in ToId()
             foreach (KeyValuePair<int, ItemType> entry in GetDict())
                 DictReverse.Add(entry.Value, entry.Key);
+
+            DictReverse[ItemType.Unknown] = -2;
+            DictReverse[ItemType.Null] = -1;
         }
 
         public ItemType FromId(int id)
         {
+            // Unknown item types may appear of Forge servers for custom items
+            if (!GetDict().ContainsKey(id))
+                return ItemType.Unknown;
+
             return GetDict()[id];
         }
 
         public int ToId(ItemType itemType)
         {
-            if (itemType == ItemType.Null)
-                return -1;
             return DictReverse[itemType];
         }
     }

MinecraftClient/Inventory/ItemType.cs

@@ -12,7 +12,8 @@ namespace MinecraftClient.Inventory
     /// </summary>
     public enum ItemType
     {
-        Null = -1, // Unspecified item type
+        Unknown = -2, // Unsupported item type (Forge mod custom item...)
+        Null = -1,    // Unspecified item type (Used in the network protocol)
 
         AcaciaBoat,
         AcaciaButton,