core, plugins: host.getClient now raise an exception instead of returning None when no profile is found, plugins have been adapted consequently and a bit cleaned

src/plugins/plugin_misc_room_game.py

@@ -427,9 +427,6 @@ class RoomGame(object):
             d.addCallback(roomJoined)
 
         client = self.host.getClient(profile)
-        if not client:
-            error(_('No client for this profile key: %s') % profile_key)
-            return
         client.client_initialized.addCallback(lambda ignore: afterClientInit(room_jid_s))
 
     def userJoinedTrigger(self, room, user, profile):