Cleanup fix

Author: Csantucci

Source/Orts.Simulation/Simulation/AIs/AI.cs

@@ -1330,7 +1330,7 @@ private void RemoveTrains()
                             car.IsPartOfActiveTrain = false;  // to stop sounds
                             // remove continers if any
                             if (car.FreightAnimations?.Animations != null)
-                                car.FreightAnimations?.RemoveDiscreteFreightAnimations(car as MSTSWagon);
+                                car.FreightAnimations?.RemoveLoads();
                         }
                     }
                 }

Source/Orts.Simulation/Simulation/RollingStocks/SubSystems/FreightAnimations.cs

@@ -865,16 +865,16 @@ public bool CheckForMerge(int i)
         }
 
         /// <summary>
-        /// Removes discrete freight animations and containers when AI train is deleted
+        /// Removes loads (e.g. containers) when AI train is deleted
         /// </summary>
 
-        public void RemoveDiscreteFreightAnimations(MSTSWagon wagon)
+        public void RemoveLoads()
         {
             foreach (var animation in Animations)
             {
                 if (animation is FreightAnimationDiscrete discreteAnimation && discreteAnimation.Container != null)
                 {
-                    wagon.Simulator.ContainerManager.Containers.Remove(discreteAnimation.Container);
+                    Wagon.Simulator.ContainerManager.Containers.Remove(discreteAnimation.Container);
                 }
             }