Minecart Error

Put the summary of the bug you're having here

What I expected to happen was...:
The minecart would break when i had it going down rails and hitting a block.

What actually happened was...:
the minecart would be there,and you would get stuck in it, but can break the block stuck in.

Steps to Reproduce:
1. first, make a functioning rail line, and place a block at end,(might have to slant it as in a mineshaft
2. then ride in the cart
3. you get stuck in block.