Minecraft crash

My Minecraft Crashed!

What I expected to happen was...:
A minecart with a furnace to be placed

What actually happened was...:
I crashed

Steps to Reproduce:
1. Place rails in what-ever way, but must start with 3 powered rails next to two planks of wood with a button on the top plank
2. Place a minecart with a furnace on the powered rail closest to the planks
3. You should crash