Trying diver.open() for busy port of nrf52840 Dongle crashes Python

[Artyrm]

Windows, Python 3.7.3
Name: pc-ble-driver-py
Version: 0.15.0

I can connect to dongle as described in #64 .
But I noticed that if dongle serial port is left open, to say in nRF Connect, on driver.open() Python will crash on spot, no "try except" would help.