fix player is null error on game_owner_dashboard

app/models/game.py

@@ -32,7 +32,9 @@ class Game(db.Model):
 
     def last_player_locations(self, offset=None):
         # pylint: disable=not-an-iterable
-        return [player.last_location(offset=offset) for player in self.players if player.user.locations]
+        return [location for location in 
+                [player.last_location(offset=offset) for player in self.players if player.user.locations]
+                if location is not None]
 
     def last_locations(self, players, offset=None):
         '''