When trading a villager block 36, game crashes

Just do not do that.

I would just like to mention that this breaks villagers on anyone's map who uses the MCEdit filter "Create Shops" with the entry "Add Unusable Trade". This is meant to prevent villagers adding new normal villager trades to the list after trading.

If this isn't going to be fixed, could I suggest it as a feature request? 🙂

Use impossible Trades like Bedrock or more than 64 Emeralds to prevent more trades.
Technical blocks (like 36) were removed from the game.
And as far as I know, MCEdit is a 3rd party tool.

This is not resolved.
It now happens with every modified items. Including item strings.
It's affected many maps and map makers.

Map makers will need to update their maps in order for them to work for 1.7.
What do you mean with "item strings"?

Description: Rendering screen

java.lang.NullPointerException: Rendering screen
	at bcl.a(SourceFile:76)
	at bel.a(SourceFile:161)
	at bmm.b(SourceFile:852)
	at azi.ah(SourceFile:787)
	at azi.f(SourceFile:711)
	at net.minecraft.client.main.Main.main(SourceFile:152)