Cleanup compile warnings, cleanup logs, spruce up level selection menu

Assets/Scripts/Core/ItemManager.cs

@@ -13,7 +13,6 @@ namespace Core
     public class ItemManager : MonoBehaviour
     {
         private static ItemManager _instance;
-        private static bool _isQuitting;
 
         /// <summary>
         /// Singleton instance of the ItemManager. No longer creates an instance if one doesn't exist.
@@ -73,11 +72,6 @@ namespace Core
             ClearAllRegistrations();
         }
 
-        void OnApplicationQuit()
-        {
-            _isQuitting = true;
-        }
-
         private void OnSceneLoadStarted(string sceneName)
         {
             // Clear all registrations when a new scene is loaded, so no stale references persist