Worlds not loading, instead game crashes

Put the summary of the bug you're having here

at first I thought it was a problem for 14w02b but then I realized it was happening with 1.7 too

What I expected to happen was...:
My world would pad like normal

What actually happened was...:
Any minecraft version I would run

Steps to Reproduce:
1. Load any minecraft version
2. Click new world or load world
3. Stare at crash report