Missing define on ESP32 about control-surface

[tttapa]

What ESP32 board are you using? Most of them have LED_BUILTIN defined, but apparently yours does not.
I added a check to see if it's defined, so it no longer fails to compile, but keep in mind that there will be no visual feedback when an error occurs, it'll just stop working.

If this happens, enable DEBUG_OUT in src/Settings/Settings.hpp and upload the code again. It will then print the error message.

If your board doesn't have a LED_BUILTIN, the following warning will be produced:

#warning "LED_BUILTIN is not available, so it cannot blink when an error occurs"

[tttapa]

By the way, if your ESP32 board has a built-in LED, but it's not defined by the Arduino Core, you can open an issue or a pull request on espressif/arduino-esp32.

For example, this is the pins_arduino.h file of a board that is configured correctly:
https://github.com/espressif/arduino-esp32/blob/79e4339582ca0891a6e6e35220c90db613c0254d/variants/esp32thing/pins_arduino.h#L14-L15

[tarTG]

Thanks for the fast fix.