How to handle access denial?

[dani-mp]

Hi there!

What's the best way of handling an access denial?

Imagine this scenario: a working Authorization is provided, but then the user deny the access. The next URL loaded is going to be checked via the Authentication closure, but as it won't be a successful one, the closure is going to return nil, making impossible for the app to know in which state the auth flow is right now. Some providers will show a nice web page with a proper message, but others will show just an ugly HTML like this one from Google:

It'd be great to enforce a way to handle also this scenario, where the auth flow has finished, but not in a successful way. How do you handle this at the moment?