message: Resolve getStats promise even if the stream cannot be locked
diff: @@ -31,6 +31,8 @@ void StatCallWorker::Execute() {
  stream->getJSONStats([&stat_promise] (std::string stats) {
  stat_promise.set_value(stats);
  });
  + } else {
  + stat_promise.set_value(std::string("{}"));
  }
  stat_future.wait();
  stat_ = stat_future.get();
  