Destructor for InventorHATMini assumes ioe device created

[dannystaple]

When a device handle can't be created (likely due to the io already being in use), the last traceback implies "not found". I've seen this confuse people.

Eg:

Traceback (most recent call last):
  File "/home/pi/robot/tests/test_motors.py", line 5, in <module>
    board = inventorhatmini.InventorHATMini()
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pi/robotvenv/lib/python3.11/site-packages/inventorhatmini/__init__.py", line 106, in __init__
    self._pin_user_sw = gpiodevice.get_pin(self.PI_USER_SW_PIN, "IHM-SW", INPD)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pi/robotvenv/lib/python3.11/site-packages/gpiodevice/__init__.py", line 163, in get_pin
    lines = chip.request_lines(consumer=f"{consumer}-{label}", config={line_offset: settings})
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pi/robotvenv/lib/python3.11/site-packages/gpiod/chip.py", line 331, in request_lines
    req_internal = cast(_ext.Chip, self._chip).request_lines(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: [Errno 16] Device or resource busy
Exception ignored in: <function InventorHATMini.__del__ at 0xf7008118>
Traceback (most recent call last):
  File "/home/pi/robotvenv/lib/python3.11/site-packages/inventorhatmini/__init__.py", line 162, in __del__
    self.ioe.reset()
    ^^^^^^^^
AttributeError: 'InventorHATMini' object has no attribute 'ioe'

This is because a failure has occurred before ioe is assigned. It would be more sensible to assign a None to this object until it is ready (in the class constructor), and then have an if guard on

inventorhatmini-python/inventorhatmini/__init__.py

Line 162 in de6f82f

self.ioe.reset()

.

Eg:

    def __del__(self):
        if self.ioe:
            self.ioe.reset()

It would still fall to the user to make sense of the device busy, but that might hopefully lead them to check for still-running processes.

[Gadgetoid]

Thank you. And agreed, do you want to raise a PR for this?