diff --git a/Engine.Core/GameManager.cs b/Engine.Core/GameManager.cs
index d83d95d..dbc7394 100644
--- a/Engine.Core/GameManager.cs
+++ b/Engine.Core/GameManager.cs
@@ -37,7 +37,20 @@ public class GameManager : IEntity
 
     public bool Initialized => _initialized;
     public IList<IGameObject> GameObjects => _gameObjects;
-    public IStateEnable StateEnable { get { if (_stateEnable is null) Assign(new StateEnableFactory().Instantiate(this)); return _stateEnable; } }
+    public IStateEnable StateEnable
+    {
+        get
+        {
+            if (_stateEnable is null)
+            {
+                Assign(new StateEnableFactory().Instantiate(this));
+                if (_stateEnable is null)
+                    throw NotAssignedException.From(this, _stateEnable);
+            }
+
+            return _stateEnable;
+        }
+    }
 
     public void RegisterGameObject(IGameObject gameObject)
     {