Tried to launch world, repeatedly crashes upon terrain generation

Put the summary of the bug you're having here

What I expected to happen was..:
The world would open and i would play as normal

What actually happened was...:
It started to open the world but then minecraft crashed and the launcher opened and showed the crash report

Steps to Reproduce:
1. I launched minecraft
2. I clicked single player
3. I clicked on my world "Skyblocks 2.1"
4. the world started opening and then crashed