fix my fkup

gameserver/models/cache.py

@@ -233,7 +233,7 @@ def __str__(self) -> str:
         # todo optimize by using select_related
         # self.objects.select_related("participation__team__name")
         if self.participation.team is None:
-            return self.participation.user.username
+            return self.participation.participants.first().username
         return self.participation.team.name
 
     @classmethod