chore: added todo for a rare bug

Engine.Core/Helpers/Event.cs

@@ -5,6 +5,12 @@ using Engine.Core.Debug;
 
 namespace Engine.Core;
 
+// TODO!: every reverse loop has a chance to have more than 1 unsubscription,
+// for (int i = listeners.Count - 1; i >= 0; i--) 
+// can be replaced with 
+// for (int i = listeners.Count - 1; i >= 0; i = Math.Min(i - 1, listeners.Count - 1))
+// but this would causes possible double calls on already called callbacks, find a better method.
+
 /// <summary>
 /// Represents a simple event with no parameters.
 /// <para>Example usage:</para> 

Engine.Core/Systems/UniverseEntranceManager.cs

@@ -17,8 +17,8 @@ public class UniverseEntranceManager : Behaviour
     {
         enterUniverses.Assign(universe);
 
-        foreach (IUniverseObject universeObject in Universe.UniverseObjects)
+        foreach (IUniverseObject universeObject in universe.UniverseObjects)
-            OnUniverseObjectRegistered(Universe, new(universeObject));
+            OnUniverseObjectRegistered(universe, new(universeObject));
 
         universe.OnUniverseObjectRegistered.AddListener(OnUniverseObjectRegistered);
         universe.OnUniverseObjectUnRegistered.AddListener(OnUniverseObjectUnRegistered);
@@ -28,8 +28,8 @@ public class UniverseEntranceManager : Behaviour
     {
         enterUniverses.Unassign();
 
-        foreach (IUniverseObject universeObject in Universe.UniverseObjects)
+        foreach (IUniverseObject universeObject in universe.UniverseObjects)
-            OnUniverseObjectUnRegistered(Universe, new(universeObject));
+            OnUniverseObjectUnRegistered(universe, new(universeObject));
 
         universe.OnUniverseObjectRegistered.RemoveListener(OnUniverseObjectRegistered);
         universe.OnUniverseObjectUnRegistered.RemoveListener(OnUniverseObjectUnRegistered);

Engine.Core/Universe.cs

@@ -120,8 +120,8 @@ public class Universe : BaseEntity, IUniverse
     protected override void FinalizeInternal()
     {
         base.FinalizeInternal();
-        for (int i = UniverseObjects.Count; i >= 0; i--)
+        for (int i = UniverseObjects.Count - 1; i >= 0; i--)
-            UniverseObjects[i].Finalize();
+            Remove(UniverseObjects[i]);
     }
 
     public void Update(UniverseTime engineTime)

Engine.Core/UniverseObject.cs

@@ -100,14 +100,14 @@ public class UniverseObject : BaseEntity, IUniverseObject
         return true;
     }
 
-    public void AddChild(IUniverseObject parent)
+    public void AddChild(IUniverseObject child)
     {
-        if (_children.Contains(parent))
+        if (_children.Contains(child))
             return;
 
-        _children.Add(parent);
+        _children.Add(child);
-        parent.Parent = this;
+        child.Parent = this;
-        OnChildrenAdded?.Invoke(this, new(parent));
+        OnChildrenAdded?.Invoke(this, new(child));
     }
 
     public void RemoveChild(IUniverseObject child)