if you fail to join a lobby using a lobby code/the "Join Friend" button, you get a network error numbered 14, which i feel isn't very useful, and the only way to get a better understanding of the error codes is via this discord. i think you should get different messages depending on if the lobby doesn't exist, if the lobby is full, or if the lobby has a game ongoing. it'd make trying to join lobbies in the #🔦・room-codes a bit easier since you'd be able to tell if games are still going or not.
also, while i'm not sure how feasible this is, it'd be nice if you could enter a "wait list" when attempting to join a lobby (via lobby code) that has a game ongoing.