AttributeError: 'NoneType' object has no attribute 'get'

[MarcSkovMadsen]

panel==1.5.5

I'm trying to configure azure oauth. Its hard for me to understand how to configure the azure side.

But I do currently see a bug in Panel

Traceback (most recent call last):
  File "/home/jovyan/repos/mt-ai-assistant/.venv/lib/python3.11/site-packages/panel/auth.py", line 225, in _fetch_access_token
    response = await http.fetch(req)
               ^^^^^^^^^^^^^^^^^^^^^
tornado.httpclient.HTTPClientError: HTTP 401: Unauthorized

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/jovyan/repos/mt-ai-assistant/.venv/lib/python3.11/site-packages/tornado/web.py", line 1790, in _execute
    result = await result
             ^^^^^^^^^^^^
  File "/home/jovyan/repos/mt-ai-assistant/.venv/lib/python3.11/site-packages/panel/auth.py", line 391, in get
    user = await self.get_authenticated_user(**params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jovyan/repos/mt-ai-assistant/.venv/lib/python3.11/site-packages/panel/auth.py", line 141, in get_authenticated_user
    user, _, _, _ = await self._fetch_access_token(
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jovyan/repos/mt-ai-assistant/.venv/lib/python3.11/site-packages/panel/auth.py", line 228, in _fetch_access_token
    self._raise_error(e.response, status=401)
  File "/home/jovyan/repos/mt-ai-assistant/.venv/lib/python3.11/site-packages/panel/auth.py", line 455, in _raise_error
    body.get('error_description', str(body)),
    ^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'get'

I do believe the Panel code does not handle the 401 error and body==None well:

[philippjfr]

Fixed in #7587