message: fix: don't join already joined rooms
diff: @@ -206,7 +206,7 @@ class MultiUserJoinDialog {
  }
  private testInputValues(): Promise<JID | void> {
  - let room = this.roomInputElement.val();
  + let room = <string>this.roomInputElement.val();
  let nickname = this.nicknameInputElement.val() || this.defaultNickname;
  let server = this.serverInputElement.val();
  @@ -228,14 +228,15 @@ class MultiUserJoinDialog {
  room += '@' + server;
  }
  - //@TODO test if we already joined the room
  - // if () {
  - // $('<p>').addClass('jsxc_warning').text($.t('You_already_joined_this_room')).appendTo(dialog.find('.jsxc_msg'));
  - // }
  + let roomJid = new JID(room);
  +
  + if (this.account.getContact(roomJid)) {
  + return Promise.reject('You_already_joined_this_room');
  + }
  this.dom.find('input[name="room-jid"]').val(room);
  - return Promise.resolve(new JID(room));
  + return Promise.resolve(roomJid);
  }
  private requestRoomInfo = (room: JID) => {
  