When my minecraft is about to start it wont it just goes to a crash report.after i click play on the launcher it just loads a littloe then goes to crash report

Put the summary of the bug you're having here

What I expected to happen was...:
i expected my minecraft to start
What actually happened was...:
it got a crash report on the launcher
Steps to Reproduce:
1. click play
2. wait
3. then u get crash report