So I have 11 crash reports, I will link the last two. All I can say about it is I thought it was due to loading new chunks, however I explored an already loaded area and I am stuck there before it crashes. Chunks disappear so I can see the sky, then it crashes soon after.
I have never experienced crashes so this is all new to me, and I can't find similar reports although I'm not sure how to find better matching results to my issue.
Edit: forgot to mention, world save backup works fine however the problem persists after playing the game for a bit.
Game worked in 1.13 pre 1, but started crashing in pre 2.
Allocating more memory fixed nothing.