I go to my world it loads but everytime it pops up a Java error

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here *I thought it i will play my world

What actually happened was...:
Describe what happened here *What happen itpops up a Java error

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