`UserInfo` endpoint lookup never returns

As part of the OIDC login flow, during the backchannel exchange to get the access and id token (assuming you are in the auth code flow, but that's not relevant to the issue), one can perform a check against the UserInfo endpoint of the OIDC provider to check that the sub claim of the obtained ID token matches the one of the userinfo associated to the access token.

However, in the case of NSS, a lookup at https://inrupt.net/.well-known/openid-configuration shows that the userinfo endpoint exists, but a GET to https://inrupt.net/userinfo just hangs, and never get either a success or an error response. This prevents proper functioning of some OIDC libraries, and requires to be worked around. Should this be fixed in the NSS repo, or rather at the oidc-op level ?

Reproduce the hanging GET request at https://inrupt.net/userinfo and compare it with the advertised endpoint in https://inrupt.net/.well-known/openid-configuration. Trace whether NSS or oidc-op owns the UserInfo behavior; done means the endpoint returns either a success or an error response so OIDC libraries can complete their validation.