event_authentication_failure_level=LOG_EMERG does not produce log output on auth failure

When configured with event_authentication_failure_level=LOG_EMERG, authentication failures no longer produce log messages. The expected behavior would be to either receive an error that the log level is not supported if syslog=true is not used or that the log line would be output with emerg: as the severity. The same applies to LOG_CRIT as well.