Fixes to avoid MBIM_DEVICE_SIGNAL_ERROR emitted at the wrong time
@maciejsszmigiero FYI. Thanks for finding this, and thanks for the suggested fixes.
This approach is a bit different to the one you took in !193 (714e193c), instead of delaying the unblock of the signal, we completely remove its need. The idea is that if the user has expressed their desire to force-close a MBIM device, we should avoid emitting the SIGNAL_ERROR
signal altogether after the response message has been processed. I think the solution is a bit more robust, because I don't think we can assume the assert you added in !193 (714e193c) is always valid.