PHP8.1 failing test

[aspark21]

PHP8.1 / MOODLE_403_STABLE

Manage outages/View an outage which should open in a new window or tab.

Then I should be in a new window: 8192: explode(): Passing null to parameter #2 ($string) of type string is deprecated in /var/www/html/auth/outage/tests/behat/behat_auth_outage.php line 335

https://github.com/catalyst/moodle-auth_outage/blob/MOODLE_39_STABLE/tests/behat/behat_auth_outage.php#L335