Can not execute event observer '\local_alp\observer::test_course_viewed'

• line 164 of /lib/classes/event/manager.php: call to debugging()
• line 75 of /lib/classes/event/manager.php: call to core\event\manager::process_buffers()
• line 795 of /lib/classes/event/base.php: call to core\event\manager::dispatch()
• line 3679 of /course/lib.php: call to core\event\base->trigger()
• line 99 of /index.php: call to course_view()