When you use the give command to get a written book and don't specify any nbt-data you get a book that has no author. If you try to make a copy of it the game crashes.
Steps to reproduce:
1. give your self a written book using the command "/give playername minecraft:written_book"
2. when you try to craft a copy of this book the game crashes
What probably causes this bug:
When the game tries to make a copy of the book it also tries to copy the author name of the book but because the book has no author it throws a NullPointerException.