48279 - Participants tab fails to render when the percentage column is enabled

[lorenzgith]

https://mantis.ilias.de/view.php?id=48279

As soon as the optional column for the achieved percentage is switched on in the participants table of a test, the whole tab stops rendering:

number_format(): Argument #1 ($num) must be of type int|float, null given
in UI/src/Implementation/Component/Table/Column/Number.php:68

percent_of_available_points is a number() column, but the row value is built with the null-safe operator and no fallback, so a participant without an attempt yields null. The renderer then hands that null to number_format() and the whole table fails, not just the affected cell.

The neighbouring values in the same method all do provide a fallback (total_attempts ?? 0, test_passed ?? false, total_time_on_task ?? ''); only the percentage lacks one. This adds ?? 0 accordingly.

If an empty cell is preferred over a zero for participants without an attempt, letting the number column render null would be the alternative, but the fallback is the smaller and more consistent change.

[kergomard]

Thank you very much for the PR @lorenzgith !

I picked your changes manually, as I wanted to have a value that was consistent with the return type of the function, but you are clearly still the author.

Best,
@kergomard