Crash

Put the summary of the bug you're having here

What I expected to happen was...:
to join my singleplayer world
What actually happened was...:
The game crashed

Steps to Reproduce:
1. Open minecraft for the first time since 2014
2. Play offline because of some reason I could not play online because of some error
3. Make offline world.
4. Start loading the world.
5. The world crashes and i get the message you are seeing.
6. Please halp me