In Koha/REST/V1/OAuth/Client.pm, when there's an error, we redirect to another page with a URL parameter "auth_error". Here's some example errors: "No configuration found for your provider"; "wrong_csrf_token" "No configuration found for your email domain" "User cannot access this resource" <An exception caught during $c->oauth2->get_token_p> Only the errors after "wrong_csrf_token" are escaped.