Error message if email is missing

[phavekes]

This issue is imported from pivotal - Originaly created at Dec 2, 2020 by Peter Havekes

When no email-adress is returned (or the SAML attribute name is incorrect) the user is returned to the starting page of the AzureMFA gssp, and thinks he's in a loop. A correct error message should de shown

Dec  1 17:37:55 app11.stepup.coin.surf.net stepup-azure-mfa[32267]: {"channel":"request","level":"CRITICAL","message":"Uncaught PHP Exception Error: \"Call to a member function getEmailAddress() on null\" at /opt/stepup/Stepup-Azure-MFA-1.3.1-20201106151639Z-3866bfee49423079300531e89eb69709d25be792/src/Surfnet/AzureMfa/Application/Service/AzureMfaService.php line 193","context":{"exception":{"class":"Symfony\\Component\\Debug\\Exception\\FatalThrowableError","message":"Call to a member function getEmailAddress() on null","code":0,"file":"/opt/stepup/Stepup-Azure-MFA-1.3.1-20201106151639Z-3866bfee49423079300531e89eb69709d25be792/src/Surfnet/AzureMfa/Application/Service/AzureMfaService.php:193"}},"extra":{"art":"13661","server":"azuremfa.surfconext.nl","application":"azure-mfa","request_id":"aef49e1e1bed568ec29de999497caa2d"}}