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

Assets/Scripts/PuzzleS/PuzzleManager.cs

@@ -19,7 +19,6 @@ namespace PuzzleS
     public class PuzzleManager : MonoBehaviour
     {
         private static PuzzleManager _instance;
-        private static bool _isQuitting;
 
         [SerializeField] private float proximityCheckInterval = 0.02f;
 
@@ -496,10 +495,5 @@ namespace PuzzleS
         {
             return _isDataLoaded;
         }
-
-        void OnApplicationQuit()
-        {
-            _isQuitting = true;
-        }
     }
 }