This report is based on MC-34943

The bug

When you have a villager trading an item for an item with the Count of 0 and you Shift-click on the trade when you have a empty inventory, Minecraft crashes.

How to reproduce

1. Use the following command

    /summon Villager ~ ~1 ~ {Health:0.1f,Offers:{Recipes:[{buy:{id:"stone",Count:0b},sell:{id:"dirt",Count:1b},maxUses:2147483647,uses:0}]}} 
   

2. Empty your inventory
3. Give yourself one stone block
4. Place the stone block in the trading window and Shift-click the offered item (dirt)