Contrary to what the error might imply. This is not a world corruption. I'm getting this crash with any backup I try to load.
I had to remove the mod to be able to continue playing
https://hastebin.com/ovoyiqiwuw.rb

I had the same issue. BetterEnd also causes all the vanilla end biomes to be registered twice. The moment I removed this mod (after a full week & hundreds of test runs), the problem vanished.