game: core: change player to player.isconnected

befort: if a player is disconnected he doesn't have an object
after: he have un object with a socket == None

games/objects/GameManager.py

@@ -21,6 +21,4 @@ class GameManager():
         
         self._game_list.append(game)
         
-        return game
-            
-        
+        return game