message: Fix Asan issue
diff: @@ -56,14 +56,16 @@ void middleman::stop() {
  for (const auto& backend : backends_)
  backend->stop();
  mpx_->shutdown();
  - if (mpx_thread_.joinable())
  - mpx_thread_.join();
  + // TODO: Implement shutdown for multiplexer running in own thread!
  + // if (mpx_thread_.joinable())
  + // mpx_thread_.join();
  + mpx_->run();
  }
  void middleman::init(actor_system_config& cfg) {
  if (auto err = mpx_->init()) {
  CAF_LOG_ERROR("mgr->init() failed: " << system().render(err));
  - CAF_RAISE_ERROR("mpx->init failed");
  + CAF_RAISE_ERROR("mpx->init() failed");
  }
  if (auto node_uri = get_if<uri>(&cfg, "middleman.this-node")) {
  auto this_node = make_node_id(std::move(*node_uri));
  