crashes

Put the summary of the bug you're having here

*What I expected to happen was to log on to minecraft and play some speedruns
Describe what you thought should happen here i should of got practice and went to bed

*What actually happened was my game booted up nothing wrong i got in the game and it crashed when i took a step forward
Describe what happened here i loaded p my game and i got ready to play then it randomly crashed but i could see the world before it did

Steps to Reproduce:
1. boot up minecraft
2. make a new world
3. step forward
4. crash!!!