Put the summary of the bug you're having here

What I expected to happen was...:
placing an item in a furnace to smelt it.

*sidenote: the map has been changed from various versions. Normally, chunks are generated and previous fragments of the map are eliminated but it has never crashed when using a furnace as it is normally used.

What actually happened was...:
the game crashed a third time when an item was placed in the slot to smelt it.

Steps to Reproduce:
1. get a furnace
2. place an item in either slot of the furnace