Chest Crash.

I was playing on my Creative world (superflat preset Overworld) and I had
put an item in a chest in 1.6.4 and when I went back to 1.7.2 and opened the chest, the whole game just crashed.

Steps to Reproduce
1. Put an item in a chest in 1.6.4 that doesn't exist in 1.7.2 (such as something called tile.null.name)
2. Reload the game in 1.7.2 and open the chest.