When using a non-[a-z0-9/._-]-character as biome in a superflat preset, the game crashes.
- Open MC 1.14.4 or later
- Create new superflat world
- Choose a preset that uses a non-[a-z0-9/._-] character as biome (e.g. minecraft:air;*;)
- Click Done (or whatever button it was)
→ The game crashes instead of giving a proper error message