Gajim should warn user if they try to join a room with an empty nickname
If a user tries to join a room with an empty nickname, Gajim sends an XML request without specifying any nickname and it does not receive any answer, and the user may think the conference server is down or something. I suggest Gajim should check if there's a non-empty nickname in the "join room" form, and if the nick is empty, warn the user that it won't work without a nick.