[requests] Improve exception class constructors

[intgr]

Somewhat related to #8989.

Relevant code: https://requests.readthedocs.io/en/latest/_modules/requests/exceptions/#RequestException

[JelleZijlstra]

Should we make the arguments also optional on HTTPError?

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

cloud-init (https://github.com/canonical/cloud-init)
+ tests/unittests/sources/azure/test_errors.py:169: error: Missing named argument "request" for "HTTPError"  [call-arg]
+ tests/unittests/sources/azure/test_errors.py:169: error: Missing named argument "response" for "HTTPError"  [call-arg]
+ tests/unittests/sources/azure/test_imds.py:64: error: Missing named argument "request" for "HTTPError"  [call-arg]
+ tests/unittests/sources/test_azure.py:343: error: Missing named argument "request" for "HTTPError"  [call-arg]

paasta (https://github.com/yelp/paasta)
+ paasta_tools/mesos_maintenance.py:213: error: Missing named argument "request" for "HTTPError"  [call-arg]
+ paasta_tools/mesos_maintenance.py:213: error: Missing named argument "response" for "HTTPError"  [call-arg]

apprise (https://github.com/caronc/apprise)
+ test/helpers/rest.py:63: error: Missing named argument "request" for "HTTPError"  [call-arg]
+ test/helpers/rest.py:63: error: Missing named argument "response" for "HTTPError"  [call-arg]
+ test/test_attach_http.py:59: error: Missing named argument "request" for "HTTPError"  [call-arg]
+ test/test_attach_http.py:59: error: Missing named argument "response" for "HTTPError"  [call-arg]
+ test/test_config_http.py:54: error: Missing named argument "request" for "HTTPError"  [call-arg]
+ test/test_config_http.py:54: error: Missing named argument "response" for "HTTPError"  [call-arg]

[srittau]

Should we make the arguments also optional on HTTPError?

Why add HTTPError.__init__() at all? It's just inherited in the implementation.

[intgr]

Why add HTTPError.__init__() at all? It's just inherited in the implementation.

#8989 created an assumption that request/response attrs are always present and not None in HTTPError (they're optional in other error classes). That was done specifically to reduce regressions in mypy_primer (because users had already made this assumption): #8989 (comment)

class HTTPError(RequestException):
    request: Request    # <-- can't be None
    response: Response  # <-- can't be None

That assumption is true for errors originating from requests library proper, but as can be seen here, does not hold for third party code raising these exceptions.

Relaxing HTTPError.__init__ isn't correct, but maybe it's a useful tradeoff between introducing regressions and accuracy. I'll leave it up to you, maybe you have a better gut feeling for making such tradeoffs.

[srittau]

It's a tradeoff. The primer output is a bit concerning, although most of the problems seem to be in test code. I'm fine with this change, despite the primer output. Otherwise we should revert the | None annotations in HTTPError, which is probably worse.