map unload fix when changing scenes

Source/Game/Level/Q3MapImporter.cs

@@ -423,16 +423,8 @@ namespace Game
 
         private void UnloadMap()
         {
-            IEnumerable<Actor> GetChildrenRecursive(Actor actor)
-            {
-                foreach (var act in actor.GetChildren<Actor>())
-                {
-                    yield return act;
-
-                    foreach (var child in GetChildrenRecursive(act))
-                        yield return child;
-                }
-            }
+            if (!worldSpawnActor)
+                return;
 
             var virtualAssets = new List<BinaryAsset>();
             var allActors = GetChildrenRecursive(worldSpawnActor).ToList();
@@ -450,6 +442,17 @@ namespace Game
 #if FLAX_EDITOR
             Level.SceneUnloading -= OnSceneUnloading;
 #endif
+
+            IEnumerable<Actor> GetChildrenRecursive(Actor actor)
+            {
+                foreach (var act in actor.GetChildren<Actor>())
+                {
+                    yield return act;
+
+                    foreach (var child in GetChildrenRecursive(act))
+                        yield return child;
+                }
+            }
         }
 
         private void LoadMap(bool forceLoad)