I had a world in regular 1.15.2, then I played the snapshot where I opened a nether portal that went to a warped forest. When I turned back to the regular 1.15.2 of course the place in the nether was very different, but the problem is that when I go in a certain direction (other directions are fine) the game crashes giving me the text "The game crashed whilst exception generating new chunk Error: java.lang.NullPointerException: Exception generating new chunk"
I'm sure this happened before, but I didn't find any solutions updated for the new 1.15.2 version, and I don't know if there's something different about the issue since it never happened to me before.
I tried to do the same thing that the people with the same problem did in the previous versions of the game, deleting the region file related to the chunck error, but it didn't work and the file came back in the DIM-1 folder.
If you go to a snapshot, explore a biome that is not in the normal version, and go back to the normal version is pretty risky. It will try to load a biome ID that not exist. Then it crashes.