response_info not initialized correctly sometimes

[angelakis]

In authorization's post_authentication method, there's some error handling before creating response_info and filling the return_uri entry etc., for example here:

oidcendpoint/src/oidcendpoint/oidc/authorization.py

Line 538 in 5929fde

response_info, "access_denied", "{}".format(err.args)

The response_info is initialized in line 555 and in 566 the return_uri is filled.

As a result, when do_response is called, there's an exception raised in

oidcendpoint/src/oidcendpoint/endpoint.py

Line 422 in 5929fde

resp = _response.request(kwargs["return_uri"], True)

as return_uri is considered to always be there.

We could say that the app using oidcendpoint could fill the return_uri to avoid the error, but I feel it would be better if in post_authentication the response_info was filled at the beginning rather than in the middle of the method.

[peppelinux]

If we have that value first... Yes, we could Simply fill this at the begin. Have you already done a PR for this or should we try to analyze if there would be some warnings on this?