message: udp_connection: fix for segfault on close
diff: @@ -18,7 +18,7 @@ UdpConnection::UdpConnection(DroneLinkImpl *parent,
  _remote_port_number(remote_port_number),
  _mutex(),
  _socket_fd(-1),
  - _recv_thread(),
  + _recv_thread(nullptr),
  _should_exit(false)
  {
  if (_local_port_number == 0) {
  @@ -88,8 +88,11 @@ DroneLink::ConnectionResult UdpConnection::stop()
  _should_exit = true;
  shutdown(_socket_fd, SHUT_RDWR);
  + if (_recv_thread) {
  _recv_thread->join();
  delete _recv_thread;
  + _recv_thread = nullptr;
  + }
  close(_socket_fd);
  