There are some serious issues in the file "board.c" that relate to LEDS_NUMBER.
If I create a custom board with no LEDs then I set LEDS_NUMBER to in my custom boards,h. However this creates a number issues:
1. There are no routines defined for (eg) bsp_board_led_on() and this generates a compiler error. Perhaps an #else clause can be added that provides dummy routines.
2. The code to initialise the GPIO output voltage on nRF52840 is within the block defined by LEDS_NUMBER, therefore in a board with no LEDS this code would be missing. It should be moved.