Call to a member function get() on null in MaintenanceMode->getSiteMaintenanceMessage()

I have reviewed the patch in #2 and tested in on Drupal 10.0.9 (by use of mglaman/composer-drupal-lenient) and Drupal 9.5.9 and confirms it stops the site from executing a fatal error when a non-exempt page is visited in maintenance mode.

Automatically closed - issue fixed for 2 weeks with no activity.