I logged into mc.pistonmc.com and it just crashes

Put the summary of the bug you're having here

I expected to be able to play on the server but the game just crashes
Describe what you thought should happen here
I thought that it would let me play on the server
What actually happened was...:
Describe what happened here
my game crashes as soon as I log on
Steps to Reproduce:
1. open minecraft
2. multiplayer
3. mc.pistoncm.com
and it crashes my game