Attribute error when generate API documentation

[Keda87]

First of all, thank you for writing this excellent package. 👍

I'm developing a new project using this package but I got an error when creating API documentation using DRF built-in documentation following this docs.

These are my dependency information that I used.

django==2.1.5
djangorestframework==3.9.1
djangorestframework-jsonmask==0.1.1

And here is the stacktrace

Request Method: | GET
-- | --
http://127.0.0.1:5012/
2.1.5
AttributeError
'NoneType' object has no attribute 'GET'

Django Version: | 2.1.5
-- | --
AttributeError
'NoneType' object has no attribute 'GET'
/Users/adiyatmubarak/.virtualenvs/88user_service-eQNupJW0/lib/python3.7/site-packages/rest_framework_jsonmask/views.py in get_serializer_context, line 40