IIrc compress_type could be 3?

[ch-yx]

Amulet-Core/amulet/level/formats/anvil_world/region.py

Lines 286 to 293 in f81f423

	@staticmethod
	def _decompress(compress_type: int, data: bytes) -> nbt.NBTFile:
	"""Convert a bytes object into an NBTFile"""
	if compress_type == world_utils.VERSION_GZIP:
	return nbt.load(gzip.decompress(data), compressed=False)
	elif compress_type == world_utils.VERSION_DEFLATE:
	return nbt.load(zlib.decompress(data), compressed=False)
	raise ChunkLoadError(f"Invalid compression type {compress_type}")

last time i check minecraft code, compress_type may be 3.
Im not sure if this value is still allowed.

[ch-yx]

ah it is there.
21w17a\client\net\minecraft\world\level\chunk\storage\RegionFileVersion.java
seems that it is still here in 21w17a