Fix fatal when fetching questions for a lesson with no quiz

[donnapep]

Summary

A lesson without a quiz makes Sensei_Lesson::lesson_quizzes() return null. lesson_quiz_questions() casts that to the empty string '' and passes it to Sensei()->quiz_submission_repository->get( int $quiz_id, int $user_id ). The non-numeric '' cannot coerce to int, throwing:

PHP Fatal error: Uncaught TypeError: Argument 1 passed to ...Submission_Repository::get() must be of the type int, string given

All four submission repositories type-hint int, so this is independent of the HPPS (tables vs. comments) configuration.

The crash surfaces through usage tracking (Sensei_Usage_Tracking_Data::get_quiz_stats()), which loops over every published lesson — any published lesson with no quiz triggers it. Latent since the 4.7.2 refactor that swapped the legacy questions_asked comment-meta lookup (implicitly guarded by an existing user status) for the typed repository call.

Fix

Cast the quiz and user IDs to int at the call site. For a quiz-less lesson this yields get( 0, 0 ), which returns null and falls through to the existing no-submission branch — behaviour for real quizzes is unchanged.

Test plan

• On a fresh install with a published lesson that has no quiz, trigger usage tracking (sensei_core_jpo_send cron / page load) and confirm no TypeError is logged.
• Confirm quizzes with submissions still render the questions in the order they were asked.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Prevents a PHP TypeError when Sensei_Lesson::lesson_quiz_questions() attempts to fetch a quiz submission for lessons where the resolved quiz ID (and/or user ID) can be empty, which can surface during usage tracking.

Changes:

• Cast $quiz_id and $user_id to int when calling quiz_submission_repository->get() to avoid passing a non-numeric string.
• Add a changelog entry documenting the fatal fix.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
includes/class-sensei-lesson.php	Ensures typed repository call receives ints to avoid TypeError when IDs are empty/non-numeric.
changelog/fix-lesson-quiz-questions-empty-quiz-id	Documents the fix as a patch-level “fixed” change.

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