TypeError expected string or bytes-like object

[ignacionf]

Hello. I am using your library to detect mobile devices but every now and then I get the following error:

Traceback (most recent call last):
  File "/opt/app/*************/venv/lib/python3.8/site-packages/django/core/handlers/exception.py", line 56, in inner
    response = get_response(request)
  File "/opt/app/*************/venv/lib/python3.8/site-packages/sentry_sdk/integrations/django/middleware.py", line 176, in __call__
    return f(*args, **kwargs)
  File "/opt/app/*************/venv/lib/python3.8/site-packages/mobiledetect/middleware.py", line 10, in __call__
    self.process_request(request)
  File "/opt/app/*************/venv/lib/python3.8/site-packages/mobiledetect/middleware.py", line 17, in process_request
    request.device['is_mobile'] = detector.is_mobile()
  File "/opt/app/*************/venv/lib/python3.8/site-packages/mobiledetect/detection.py", line 46, in is_mobile
    return self.match_detection_rules()
  File "/opt/app/*************/venv/lib/python3.8/site-packages/mobiledetect/detection.py", line 105, in match_detection_rules
    if self.match(_regex, user_agent):
  File "/opt/app/*************/venv/lib/python3.8/site-packages/mobiledetect/detection.py", line 128, in match
    matches = re.findall(re.compile(match), user_agents if user_agents else self.user_agent.name)
  File "/usr/lib/python3.8/re.py", line 241, in findall
    return _compile(pattern, flags).findall(string)
TypeError: expected string or bytes-like object

pattern=re.compile('\x08iPhone\x08|\x08iPod\x08')
flags=0
string=None

$ pip freeze | grep mobile
django-mobile-detect==0.1