Setting up a full furnace crashes the game to the desktop.
Steps:
1. Download and install the attached world.
2. Place a chest on top of the top hopper.
Expected:
The world should not crash and the furnace should function.
Acctual:
The world crashes to the desktop as soon as the full furnace registers.
Confirmed to affect 1.2.10.1 - Trying to attain the 'Smelt Everything' achievement by attaching three hoppers with chests to a furnace will cause the game to crash.