Don't desync while the world is disposing

OpenRA.Game/Sync.cs

@@ -194,7 +194,10 @@ namespace OpenRA
 			finally
 			{
 				inUnsyncedCode = false;
-				if (sync != world.SyncHash())
+
+				// When the world is disposing all actors and effects have been removed
+				// So do not check the hash for a disposing world since it definitively has changed
+				if (!world.Disposing && sync != world.SyncHash())
 					throw new InvalidOperationException("RunUnsynced: sync-changing code may not run here");
 			}
 		}