Minecraft crashes when entering a world in 1.9

What I expected to happen was...:
To be able to play on MC worlds in 1.9.

What actually happened was...:
Every time I try to enter a world, Java and Minecraft crash, so I can't play Minecraft 1.9.

Steps to Reproduce:
1. Log in to Minecraft (v1.9)
2. Click 'singleplayer'
3. Create/join a world.