importer bug

ERROR 2021-04-26 09:43:49,950 log 2605 140209382819648 Internal Server Error: /study/1/import_subject_edit/2/execute
Traceback (most recent call last):
  File "/var/www/scheduling-system/env/lib/python3.6/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/var/www/scheduling-system/env/lib/python3.6/site-packages/django/core/handlers/base.py", line 179, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/var/www/scheduling-system/smash/web/decorators.py", line 105, in func_wrapper
    return func(thing, *args, **kwargs)
  File "/var/www/scheduling-system/smash/web/views/etl.py", line 86, in import_subject_execute
    reader.execute()
  File "/var/www/scheduling-system/smash/web/importer/importer.py", line 34, in execute
    self.study_subjects = self.reader.load_data()
  File "/var/www/scheduling-system/smash/web/importer/csv_subject_import_reader.py", line 43, in load_data
    if field.name == "nd_number" or field.name == "screening_number":
AttributeError: 'NoneType' object has no attribute 'name'