The rules for splitting lines differ in a signed book from how it's displayed in a book and quill.

Steps to reproduce

1. Write the following text in a book quill:

   This is a test book wit- h a word split across a line.

2. Sign the book.
3. Observe that the line break changed location, breaking the text.

Note

This does not occur when a newline is used instead of a space after the '-' character in the example.