message: mission: add missing return in error case
diff: @@ -488,6 +488,7 @@ void MissionImpl::set_current_mission_item_async(int current, Mission::result_ca
  if (!_parent->send_message(message)) {
  report_mission_result(callback, Mission::Result::ERROR);
  + return;
  }
  _activity = Activity::SET_CURRENT;
  