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.

Description: Updating screen events

java.lang.NullPointerException: Updating screen events
	at afc.g(SourceFile:47)
	at afm.a(SourceFile:60)
	at afv.a(SourceFile:851)
	at abh.a(SourceFile:82)
	at aau.a(SourceFile:104)
	at abq.c(SourceFile:81)
	at aai.a(SourceFile:238)
	at bnd.a(SourceFile:357)
	at bgp.a(SourceFile:515)
	at bgp.b(SourceFile:486)
	at bfk.d(SourceFile:248)
	at bfk.k(SourceFile:219)

Code analysis by marcono1234 in this comment