"New session" deck stats not always working

[schu]

The "New session" page shows stats (number of correct answers, number of incorrect answers, etc.) if a user has answered some of the questions of the selected module. In at least one OMC installation the stats component doesn't show the expected stats because the following reactive declerations do not re-run upon a change of validAnswerChoices:

openmultiplechoice/resources/js/NewSessionDeckStats.svelte

Lines 19 to 21 in 00ad17e

	$: numCorrectAnsweredQuestions = validAnswerChoices.filter(a => a.is_correct === 1 && a.help_used === 0).length;
	$: numCorrectWithHelpAnsweredQuestions = validAnswerChoices.filter(a => a.is_correct === 1 && a.help_used === 1).length;
	$: numIncorrectAnsweredQuestions = validAnswerChoices.filter(a => a.is_correct === 0).length

My understanding is that the declarations should be updated whenever validAnswerChoices gets updated, as the compiler should be able to determine that for example numCorrectAnsweredQuestions depends on the value of validAnswerChoices.

Am I missing something?

We currently use Svelte 4.2.9. So far I wasn't able to reproduce the issue locally, despite being on the same commit.