Generating a lush cave biome with this datapack installed causes the client to get disconnected from singleplayer and prevents the game window from being closed or loading a world.

To recreate:

• Create a world with this datapack installed with a seed of [1]
• Locate and teleport to a lush caves biome using the /locate command.

• The world will close before any chunks load, the world disappears from the singleplayer world list, and you can't quit game. Joining a different singleplayer world results in a hardlock. Changing resourcepacks results in a hardlock.

Note that the error does not occur in 1.20.6, so if it's a datapack error, the game isn't preventing the world from being created, like it should.