mqtt_example_init() -> Invalid initialize sequence

[nguyenlkdn]

void
mqtt_example_init(void)
{
#if LWIP_TCP
  mqtt_client = mqtt_client_new();

  mqtt_set_inpub_callback(mqtt_client,
          mqtt_incoming_publish_cb,
          mqtt_incoming_data_cb,
          LWIP_CONST_CAST(void*, &mqtt_client_info));

  mqtt_client_connect(mqtt_client,
          &mqtt_ip, MQTT_PORT,
          mqtt_connection_cb, LWIP_CONST_CAST(void*, &mqtt_client_info),
          &mqtt_client_info);
#endif /* LWIP_TCP */
}

mqtt_set_inpub_callback: This function should be called after mqtt_client_connect() is done!

Due to it will be wipe clean inside mqtt_client_connect() function
https://github.com/particle-iot/lwip/blob/master/src/apps/mqtt/mqtt.c#L1311
then whenever mqtt messages come => it got crashed at line: https://github.com/particle-iot/lwip/blob/master/src/apps/mqtt/mqtt.c#L773 NULL_PTR Callback

So it should be like this:

void
mqtt_example_init(void)
{
#if LWIP_TCP
  mqtt_client = mqtt_client_new();
  mqtt_client_connect(mqtt_client,
          &mqtt_ip, MQTT_PORT,
          mqtt_connection_cb, LWIP_CONST_CAST(void*, &mqtt_client_info),
          &mqtt_client_info);
  mqtt_set_inpub_callback(mqtt_client,
          mqtt_incoming_publish_cb,
          mqtt_incoming_data_cb,
          LWIP_CONST_CAST(void*, &mqtt_client_info));

#endif /* LWIP_TCP */
}