Custom Villager Trading Crashes Client

Custom Villager Trading Crashes Client:

I'm working on an adventure map and my custom villager trades crash when I make an offer to one. (Please fix this in the next patch)

1. Open minecraft, prepare a custom villager
2. Create a custom villager using MCEdit (I Used SethBling's custom villager trading filter)
3. Open back to minecraft, make an offer to one custom villager and the game crashes.

Again please fix this so I can enjoy 1.7.2 and map making

Description: Updating screen events

java.lang.NullPointerException: Updating screen events
	at afa.a(SourceFile:36)
	at ze.h(SourceFile:135)
	at ze.a(SourceFile:77)
	at zk.c(SourceFile:77)
	at ye.a(SourceFile:222)
	at biy.a(SourceFile:308)
	at bdd.a(SourceFile:490)
	at bdd.b(SourceFile:463)