Provide better handling in case the OIDC Response is in an invalid state

Sometimes, when authentication takes too long to be performed, or when the OIDC extension gets reloaded in a new classloader, users can get the following error :

Unfortunately, this error is not easily understandable by standard users, so the idea would be to provide a nicer error message, possibly displayed within the XWiki UI instead of through the standard error page of the servlet container.