Fix a bug that is only critical when USB data is not connected.
To install, download a .bin file and follow the guide here.
Full explanation
reset_samd21() ensures peripheral and pin state but was only done after the first main run. Without this reset, pin state is unknown and risks generating a ValueError exception due to pin in use. With USB data, the autoreset causes a reset and everything works. Without it, CircuitPython stays in the pre-repl error state.