After minor update to 4.1.9 and PHP 8.1 when trying to add a new slot (same for single slot and repeated slot) in a newly created scheduler activity, there is the error:

Exception - Undefined constant "viewurl"

When adding a new slot in a scheduler activity, where a slot has already been added, a new slot is added, but I get the following debug message (full debugging activated):

Deprecated: strip_tags(): Passing null to parameter #1 ($string) of type string is deprecated in /var/www/html/mod/scheduler/classes/model/appointment.php on line 136

Also observed/reported by others:
https://moodle.org/mod/forum/discuss.php?d=455046

Cheers

peta