Race conditions lead to errors for content permission generation #4838
Description
Describe the Bug
To edit pages on Bookstack, some people in our team use the web interface, while others store their content on git and use a Python tool to upload it to Bookstack. In the latter case, this has caused some permission issues, with permissions on the book disappearing (but not on the pages or chapters). The joint_permissions table is then empty for the targeted books. Manually creating permissions in this table, or using php artisan bookstack:regenerate-permissions fixes the issue. This has happened three times yet, the first time on January 23rd. It had never happened before we’ve used 23.12. However we are increasingly using Bookstack and the issue could have been present before.
It seems similar to #4791, but on the book, and not on the page.
Steps to Reproduce
I am not yet sure how the bug is caused exactly. What I can say is that it has always happened while using the API.
Expected Behaviour
The book should remain accessible.
Screenshots or Additional Context
No response
Browser Details
No response
Exact BookStack Version
v23.12