I have defined a new notification method in an extension.

When deactivating the extension, I do not want to delete the users notification settings.

But having a method-entry in the user_notifications table, for an unknown method (due to deactivating the extension), leads to the following error (servername etc. replaced):

Fatal error: Uncaught Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException: You have requested a non-existent service "deactivated.notification.method". Did you mean one of these: "..<list of some options>.." in /www/htdocs/w00f2a14/test.server-name.de/test/forum/vendor/symfony/dependency-injection/Container.php:348
Stack trace: 
#0 /www/htdocs/w00f2a14/test.server-name.de/test/forum/phpbb/notification/manager.php(930): Symfony\Component\DependencyInjection\Container->get('deactivated.notification.method') 
#1 /www/htdocs/w00f2a14/test.server-name.de/test/forum/phpbb/notification/manager.php(919): phpbb\notification\manager->load_object('deactivated.notification.method') 
#2 /www/htdocs/w00f2a14/test.server-name.de/test/forum/phpbb/notification/manager.php(417): phpbb\notification\manager->get_method_class('deactivated.notification.method') 
#3 /ww in /www/htdocs/w00f2a14/test.server-name.de/test/forum/vendor/symfony/dependency-injection/Container.php on line 348