Superflat presets Tunneler's Dream, Overworld, and Desert crash immediately when trying to generate with them, with error:
All other Superflat presets seem to work just fine. I made no changes to the string in the preset, everything is exactly default according to the chosen preset. All other options in the Create New World menu were default except for gamemode, which I first tried with Creative and then with Survival, and got the same result.
I tried to deobfuscate the crash files, following the tutorial on the wiki, but information was incomplete regarding what directory the files should be in, and after trying lots of things I wasn't able to make it work, so my apologies.
Crash file ending in 27.58 generated when attempting preset Tunneler's Dream
Crash file ending in 29.54 generated when attempting preset Overworld
Crash file ending in 31.16 generated when attempting preset Desert