Handle None client in game connection request

The update modifies the get_participant_game_connection method in the study server. Now, the method uses "Test" as the default host if the request client is None. This ensures that the functionality will not break when dealing with test or invalid client requests.

cooperative_cuisine/study_server.py

@@ -654,7 +654,7 @@ async def get_game_connection(
 
     """
     player_info, level_info = study_manager.get_participant_game_connection(
-        participant_id, request.client.host
+        participant_id, request.client.host if request.client is not None else "Test"
     )
     return {"player_info": player_info, "level_info": level_info}