I will explain the hopper crash I submitted today.

If you summon a villager with -1 (Green Villager) that has a career with custom working trades, completing a trade with it will crash the game in a matter of time because of a "Ticking entity".

summon Villager ~ ~ ~ {Career:1,Profession:-1,Offers:{Recipes:[{maxUses:9,buy:

,sell:{id:emerald,Count:1b}}]}} Pardon the JSON spacing, it's Atlassian's fault.

This command will summon the exact villager shown in this bug. This does not work with valid careers such as Librarians, etc.

Crash reports are attached below if anybody wants to look at them.