Navigating to book.node_child_ordering route throws Assertion Error

I attempted to replicate this issue on my end with the following setup:

Drupal Core: 10.4.3
PHP: 8.3
Book module: Upgraded from 1.0 to 2.0
After navigating to the book.node_child_ordering route that allows reordering a book page's children, I did not encounter the Assertion Error. The functionality worked as expected without any errors.

I have attached a screenshot of my test results for reference. Could you provide more details on the exact steps taken before encountering the issue?

Before encountering this issue, I upgraded book from 1.0 to 2.0. I did the necessary database updates, cleared the caches, and ran cron. Then, I navigated to a page in the book and clicked on the new "child order" tab. I should also mention the site has 4 languages, and content in this book is translated into all of them. The database is MariaDB 10.4. The site does have a custom module (but it doesn't interact with the Book module), so when I saw your comment @gurkawal, I tried to recreate the issue myself on a brand new site using the same version of Drupal and PHP, and creating content in multiple languages before upgrading Book. I was unable to recreate my problem, so I'll mark this as "closed - can't reproduce". Thanks for your help.