All the IoT hobbyists must have come across the powerful serial function like "Serial.println()" which prints the data in the serial monitor using TX/RX pins of the microcontroller board. Using this serial monitor data, developers can debug their application properly eg. "Which function/line caused the error". It has some limitations
https://www.arduino.cc/en/Main/Software
How to compile the code for ESP12:
In the arduino ide select the board as NodeMcuV1.0 ESP12E Then compile the code and upload it to ESP
How to Open Application
Now Turn the esp in running mode. it will create an access point which you can connect to. Connect to it then open any browser and enter http://192.168.1.1 it will open the application in which you can subscribe the debug channel.