When the launcher loads, it crashes

Put the summary of the bug you're having here

What I expected to happen was that the minecraft screen would come up but instead when it was on the launcher, i logged on and it said it crashed...:
Describe what you thought should happen here

What actually happened was...:
Describe what happened here

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...