message: udp_connection: check if entry is valid first
diff: @@ -135,7 +135,8 @@ bool UdpConnection::send_message(const mavlink_message_t &message)
  // on the matching link.
  const mavlink_msg_entry_t *entry = mavlink_get_msg_entry(message.msgid);
  const uint8_t target_system_id =
  - reinterpret_cast<const uint8_t *>(message.payload64)[entry->target_system_ofs];
  + (entry ? reinterpret_cast<const uint8_t *>(message.payload64)[entry->target_system_ofs] :
  + 0);
  bool send_successful = true;
  for (auto &remote : _remotes) {
  