File "/app/website/newsletter.py", line 44, in run
  f()
File "/app/website/newsletter.py", line 117, in create
  r = get_mailchimp_subscriber(email)
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/app/website/newsletter.py", line 172, in get_mailchimp_subscriber
  request_path = f'{MAILCHIMP_API_URL}/members/{get_subscriber_hash(email)}'
                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/app/website/newsletter.py", line 193, in get_subscriber_hash
  return hashlib.md5(email.encode("utf-8")).hexdigest()
                     ^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'encode'