The following warning is produced when accessing the quiz index page:

Warning: Creating default object from empty value in mod/quiz/index.php on line 129

This warning can be seen on Moodle versions: 3.9, 3.10, 3.11 and master when running PHP 7.4.x. On PHP versions lower than 7.4, this warning is not produced.

The offending line of code is:

$learningtable->data[] = 'hr';

$learningtable is not defined. It seems to be a typo.

Steps to reproduce this condition

1. Set your PHP version to 7.4.x.
2. On, Moodle, ensure that Developer mode and display errors are enabled.
3. Access a course that uses Topics format. (You should have editing rights.)
4. Turn editing on and add the Activities block to the course page.
5. Add a new quiz in section 1.
6. Add a new quiz in section 2.
7. From the Activities block, click on Quizzes to access the quiz index page: mod/quiz/index.php
8. You should see the "Warning: Creating default object from empty value" message.