Book and Quill text disappears when loading old worlds in the latest snapshot

Loaded an old world (last accessed on 24w11a) on the latest snapshot (24w19b) and text in all the books is gone.

Steps to reproduce:

1. Run version 24w11a, create a new world, get a book, write some text in a book, save world
2. Run version 24w19b, load the same world, open the same book, book is now empty