Chip select should be allowed to be null

[dearmash]

circuitpython/shared-bindings/adafruit_bus_device/spi_device/SPIDevice.c

Line 99 in 9e4dea7

mp_arg_validate_type(args[ARG_chip_select].u_obj, &digitalio_digitalinout_type, MP_QSTR_chip_select);

This line should be wrapped in the if (args[ARG_chip_select].u_obj != MP_OBJ_NULL) { check below. Or at least have its own independent check.

As of right now, constructing this without a chip select specified causes an error to be thrown.