Adding custom attributes to lesson block causes infinite loop on Update

[chvillanuevap]

This is a weird bug and I'm not exactly sure why it is happening. It might be related to WordPress/gutenberg#16850 and PopupMaker/Popup-Maker#868. Updating a Lesson post from Sensei LMS Pro while any plugin that adds attributes to Lesson blocks (I tested Popup Maker and Attributes for Blocks) causes an infinite loop. I initially reported this to Popup Maker (PopupMaker/Popup-Maker#1052), but after having the same issue with Attributes for Blocks, I now realize it's a Sensei problem.

Steps to Reproduce

1. Install Sensei Pro.
2. Install either Attributes for Blocks or Popup Maker.
3. Create a new lesson. Add a quiz with questions. For example:

<!-- wp:sensei-lms/lesson-actions -->
<div class="wp-block-sensei-lms-lesson-actions"><div class="sensei-buttons-container"><!-- wp:sensei-lms/button-view-quiz {"inContainer":true} -->
<div class="wp-block-sensei-lms-button-view-quiz is-style-default sensei-buttons-container__button-block wp-block-sensei-lms-button-view-quiz__wrapper"><div class="wp-block-sensei-lms-button-view-quiz is-style-default wp-block-sensei-button wp-block-button has-text-align-left"><button class="wp-block-button__link">View Quiz</button></div></div>
<!-- /wp:sensei-lms/button-view-quiz -->

<!-- wp:sensei-lms/button-complete-lesson {"inContainer":true} -->
<div class="wp-block-sensei-lms-button-complete-lesson is-style-default sensei-buttons-container__button-block wp-block-sensei-lms-button-complete-lesson__wrapper"><div class="wp-block-sensei-lms-button-complete-lesson is-style-default wp-block-sensei-button wp-block-button has-text-align-left"><button class="wp-block-button__link sensei-stop-double-submission">Complete Lesson</button></div></div>
<!-- /wp:sensei-lms/button-complete-lesson -->

<!-- wp:sensei-lms/button-next-lesson {"inContainer":true} -->
<div class="wp-block-sensei-lms-button-next-lesson is-style-default sensei-buttons-container__button-block wp-block-sensei-lms-button-next-lesson__wrapper"><div class="wp-block-sensei-lms-button-next-lesson is-style-default wp-block-sensei-button wp-block-button has-text-align-left"><button class="wp-block-button__link">Next Lesson</button></div></div>
<!-- /wp:sensei-lms/button-next-lesson -->

<!-- wp:sensei-lms/button-reset-lesson {"inContainer":true} -->
<div class="wp-block-sensei-lms-button-reset-lesson is-style-outline sensei-buttons-container__button-block wp-block-sensei-lms-button-reset-lesson__wrapper"><div class="wp-block-sensei-lms-button-reset-lesson is-style-outline wp-block-sensei-button wp-block-button has-text-align-left"><button class="wp-block-button__link sensei-stop-double-submission">Reset Lesson</button></div></div>
<!-- /wp:sensei-lms/button-reset-lesson --></div></div>
<!-- /wp:sensei-lms/lesson-actions -->

<!-- wp:sensei-lms/quiz {"options":{"passRequired":false,"quizPassmark":0,"autoGrade":true,"allowRetakes":false,"showQuestions":null,"randomQuestionOrder":false,"failedIndicateIncorrect":true,"failedShowCorrectAnswers":true,"failedShowAnswerFeedback":true,"buttonTextColor":null,"buttonBackgroundColor":null,"pagination":{"paginationNumber":null,"showProgressBar":false,"progressBarRadius":6,"progressBarHeight":12,"progressBarColor":null,"progressBarBackground":null},"enableQuizTimer":"","timerValue":null},"openPopupId":"1728855"} -->
<!-- wp:sensei-lms/quiz-question {"id":1610442,"title":"In Video 3, my nib kept catching on the paper and picking up fibers. What did I do to solve that problem?","answer":{"answers":[{"label":"I adjusted the brass flange of my oblique pen","correct":true},{"label":"I switched my nib","correct":false},{"label":"I started using a different ink","correct":false}]},"options":{"grade":1,"answerFeedback":"I adjusted the brass flange of my oblique pen so my nib met the paper at less of a severe angle. Having the ability to adjust the flange is a big perk of using the brass-flanged oblique pen! If you're using a straight pen, try adjusting how you hold the pen so you're able to achieve a writing angle that brings the pen closer to the paper. ","randomOrder":true}} -->
<!-- wp:sensei-lms/question-description -->
<!-- wp:paragraph {"placeholder":"Add question description or type / to choose a block."} -->
<p></p>
<!-- /wp:paragraph -->
<!-- /wp:sensei-lms/question-description -->

<!-- wp:sensei-lms/question-answers /-->

<!-- wp:sensei-lms/quiz-question-feedback-correct -->
<!-- wp:paragraph -->
<p>I adjusted the brass flange of my oblique pen so my nib met the paper at less of a severe angle. Having the ability to adjust the flange is a big perk of using the brass-flanged oblique pen! If you're using a straight pen, try adjusting how you hold the pen so you're able to achieve a writing angle that brings the pen closer to the paper. </p>
<!-- /wp:paragraph -->
<!-- /wp:sensei-lms/quiz-question-feedback-correct -->

<!-- wp:sensei-lms/quiz-question-feedback-incorrect -->
<!-- wp:paragraph -->
<p>I adjusted the brass flange of my oblique pen so my nib met the paper at less of a severe angle. Having the ability to adjust the flange is a big perk of using the brass-flanged oblique pen! If you're using a straight pen, try adjusting how you hold the pen so you're able to achieve a writing angle that brings the pen closer to the paper. </p>
<!-- /wp:paragraph -->
<!-- /wp:sensei-lms/quiz-question-feedback-incorrect -->
<!-- /wp:sensei-lms/quiz-question -->

<!-- wp:sensei-lms/quiz-question {"id":1726732,"title":"feawfew","answer":{"answers":[{"label":"aefewf","correct":true}]},"options":{"grade":1,"answerFeedback":"aefaewfaewf","randomOrder":true}} -->
<!-- wp:sensei-lms/question-description -->
<!-- wp:paragraph {"placeholder":"Add question description or type / to choose a block."} -->
<p></p>
<!-- /wp:paragraph -->
<!-- /wp:sensei-lms/question-description -->

<!-- wp:sensei-lms/question-answers /-->

<!-- wp:sensei-lms/quiz-question-feedback-correct -->
<!-- wp:paragraph -->
<p>aefaewfaewf</p>
<!-- /wp:paragraph -->
<!-- /wp:sensei-lms/quiz-question-feedback-correct -->

<!-- wp:sensei-lms/quiz-question-feedback-incorrect -->
<!-- wp:paragraph -->
<p>aefaewfaewf</p>
<!-- /wp:paragraph -->
<!-- /wp:sensei-lms/quiz-question-feedback-incorrect -->
<!-- /wp:sensei-lms/quiz-question -->

<!-- wp:sensei-lms/quiz-question /-->
<!-- /wp:sensei-lms/quiz -->

4. Click Update.
5. Update loops infinitely.

What I Expected

Update should also be called once.

What Happened Instead

Update is stuck in an infinite loop.

PHP / WordPress / Sensei LMS version

WordPress version: 6.3
PHP version: 7.4.30 (also tested on 8.1.9)
Popup Maker version: 1.18.2
Sensei LMS Pro version: 4.16.1

Browser / OS version

Google Chrome Version 115.0.5790.170 (Official Build) (arm64)

Screenshot / Video