Fixes server shutdowns

Source/Game/Maps/Map.cs

@@ -1579,7 +1579,7 @@ namespace Game.Maps
                 }
             }
 
-            foreach (Transport transport in _transports)
+            foreach (Transport transport in _transports.ToList())
                 RemoveFromMap(transport, true);
 
             _transports.Clear();

Source/Game/Maps/MapManager.cs

@@ -254,7 +254,7 @@ namespace Game.Entities
             foreach (var pair in i_maps.ToList())
             {
                 pair.Value.UnloadAll();
-                i_maps.Remove(pair.Value.GetId());
+                i_maps.Remove(pair.Key);
             }
         }