Improve feedback on nonhappy paths

[thijskh]

If you press cancel in the webauthn dialog, or wait too long because you cannot find your token, you get the generic Stepup error page:

Er is een foutmelding opgetreden met de volgende gegevens:

Tijd: 2021-01-27T10:37:56.120Z
Applicatie: webauthn.test.surfconext.nl
Request ID: 796cd344ef1763e993e46ec644bbc666
Sari: _13f049229657c64be4807885f9d6b0e00c1c3f43e1aba3330c8047e202a1
Foutcode: F113676
User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:84.0) Gecko/20100101 Firefox/84.0
IP-adres: 145.101.112.72

AbortError: The operation was aborted.

These conditions are not so exceptional to justify this and in my opinion should either be handled with a custom error page for these conditions (you pressed cancel / waited to long, button to try again?) or send the user back with the correct saml status response like e.g. yubikey does when you cancel.