Core/GameObjects: Properly set GO_FLAG_MAP_OBJECT during gameobject creation

Port From (https://github.com/TrinityCore/TrinityCore/commit/e3cf94d4fdbfae5ce99aa754bd29a0b77cd1b73d)

Source/Game/Entities/GameObject/GameObject.cs

@@ -266,9 +266,7 @@ namespace Game.Entities
 
             SetDisplayId(goInfo.displayId);
 
-            m_model = CreateModel();
-            if (m_model != null && m_model.IsMapObject())
-                AddFlag(GameObjectFlags.MapObject);
+            CreateModel();
 
             // GAMEOBJECT_BYTES_1, index at 0, 1, 2 and 3
             SetGoType(goInfo.type);
@@ -2410,14 +2408,12 @@ namespace Game.Entities
                 if (GetMap().ContainsGameObjectModel(m_model))
                     GetMap().RemoveGameObjectModel(m_model);
 
-            m_model = CreateModel();
+            RemoveFlag(GameObjectFlags.MapObject);
+            m_model = null;
+            CreateModel();
+
             if (m_model != null)
                 GetMap().InsertGameObjectModel(m_model);
-
-            if (m_model != null && m_model.IsMapObject())
-                AddFlag(GameObjectFlags.MapObject);
-            else
-                RemoveFlag(GameObjectFlags.MapObject);
         }
 
         Player GetLootRecipient()
@@ -2763,9 +2759,11 @@ namespace Game.Entities
             return IsInRange(obj.GetPositionX(), obj.GetPositionY(), obj.GetPositionZ(), dist2compare);
         }
 
-        public GameObjectModel CreateModel()
+        public void CreateModel()
         {
-            return GameObjectModel.Create(new GameObjectModelOwnerImpl(this));
+            m_model = GameObjectModel.Create(new GameObjectModelOwnerImpl(this));
+            if (m_model != null && m_model.IsMapObject())
+                AddFlag(GameObjectFlags.MapObject);
         }
 
         #region Fields

Source/Game/Entities/Transport.cs

@@ -133,7 +133,7 @@ namespace Game.Entities
             SetWorldRotation(0.0f, 0.0f, 0.0f, 1.0f);
             SetParentRotation(Quaternion.WAxis);
 
-            m_model = CreateModel();
+            CreateModel();
             return true;
         }