Keeps crashing

Put the summary of the bug you're having here

*What I expected to happen was... test Demo
Describe what you thought should happen here Play demo

*What actually happened was...:kept crashing
Describe what happened here would start to load up and then get the error message

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...Start the Minecraft program
3. ...Click on "Play Demo"