All items deleted (A bug, not help or mod)

Only effects 1.8!

What I expected to happen was...:
Kill a zombie

What actually happened was...:
My game crashed, and when i restarted and turned on my game again, everything in my inventory, furnaces, chest and everything where gone.

Steps to Reproduce:
1. Go into a minecart and let it move.
2. Punch an enemy whit a sword while riding in the minecart.
3. Game crashes and every item that is in any type of GUI is gone.