GetClient() failure always causes invalid_client error, should support internal server error too

[nerocrux]

Describe the bug

• When I implement GetClient(), I will return Internal Error for DB failure, etc... But I found out that fosite does not check what error Store.GetClient() returns, and always throws Invalid Client error.
• https://github.com/ory/fosite/blob/master/authorize_request_handler.go#L231

To Reproduce

• Intentionally returns Internal Server Error from Store

Expected behavior

• Store.GetClient() should check the error returned to it
• If it is Internal Server Error, fosite should return server_error, otherwise, return invalid_client error.

Screenshots

• none

Version:

• all versions and environments

Additional context

[nerocrux]

@aeneasr Does this make sense to you?
https://github.com/ory/fosite/compare/master...nerocrux:nerocrux/get_client_server_error?expand=1#diff-100bec18cf938f12667fb905672e72ccR231

[nerocrux]

Since change error code may cause broken change, users can just set error message using WithDebug() to let handler know what kind of error happened (bad request or internal server error).
https://github.com/ory/fosite/blob/master/client_authentication.go#L185

But in AuthorizeRequestHandler and IntrospectionRequestHandler, users can not set error message because WithDebug() are not implemented.

https://github.com/ory/fosite/blob/master/authorize_request_handler.go#L231

Is it possible to allow it?

I'll open a PR to show what I want to do.