Errors when running prepro.py

[sina-ehsani]

Dear Authors, Thank you for sharing this amazing work. Your ideas on the history of words and the fully connected attention model are inspiring.
I have tried to run your program for reproducibility, but while running the code using the docker container, this error shows up every time I ran the prepro.py. Please let me know what should I do. Thank you,

Traceback (most recent call last):
  File "prepro.py", line 101, in <module>
    vocab_tag = list(nlp.tagger.tag_names)
AttributeError: 'NoneType' object has no attribute 'tag_names'