Error in (WIP) Create Sentence Cards from Books

This app gives back this exception and finally stop the process:

Caught exception:
Traceback (most recent call last):
File “C:***\Anki2\addons21\”, line 36, in main
deck[‘mid’] = m[‘id’]
TypeError: ‘NoneType’ object is not subscriptable

Do you guys have an idea, how to bring this to work? Author won’t answer anymore.