message: Fix error propagation of publish and connect
  closes
diff: @@ -214,7 +214,7 @@ protected:
  uint16_t port) override {
  CAF_LOG_TRACE(CAF_ARG(host) << CAF_ARG(port));
  auto fd = io::network::new_tcp_connection(host, port);
  - if (fd == io::network::invalid_native_socket)
  + if (!fd)
  return std::move(fd.error());
  io::network::nonblocking(*fd, true);
  auto sssn = make_session(system(), *fd, false);
  @@ -231,7 +231,7 @@ protected:
  bool reuse) override {
  CAF_LOG_TRACE(CAF_ARG(port) << CAF_ARG(reuse));
  auto fd = io::network::new_tcp_acceptor_impl(port, addr, reuse);
  - if (fd == io::network::invalid_native_socket)
  + if (!fd)
  return std::move(fd.error());
  return make_counted<doorman_impl>(mpx(), *fd);
  }
  