I ran into an other issue(the last one was caused by me not following the install guide and setting the game's folder not the gamedata folder)
Python: Traceback (most recent call last):
File "C:\Users\HunKr\AppData\Roaming\Blender Foundation\Blender\2.91\scripts\addons\io_object_mu\import_craft\import_craft.py", line 106, in execute
return import_craft_op(self, context, **keywords)
File "C:\Users\HunKr\AppData\Roaming\Blender Foundation\Blender\2.91\scripts\addons\io_object_mu\import_craft\import_craft.py", line 80, in import_craft_op
obj = import_craft(filepath)
File "C:\Users\HunKr\AppData\Roaming\Blender Foundation\Blender\2.91\scripts\addons\io_object_mu\import_craft\import_craft.py", line 44, in import_craft
gamedata = GameData(Preferences().GameData)
File "C:\Users\HunKr\AppData\Roaming\Blender Foundation\Blender\2.91\scripts\addons\io_object_mu\import_craft\gamedata.py", line 140, in __init__
self.models = Model.Preloaded()
File "C:\Users\HunKr\AppData\Roaming\Blender Foundation\Blender\2.91\scripts\addons\io_object_mu\model\model.py", line 95, in Preloaded
preloaded = Model(None, url)
File "C:\Users\HunKr\AppData\Roaming\Blender Foundation\Blender\2.91\scripts\addons\io_object_mu\model\model.py", line 106, in __init__
obj, mu = import_mu(model, path, False, False)
File "C:\Users\HunKr\AppData\Roaming\Blender Foundation\Blender\2.91\scripts\addons\io_object_mu\import_mu\import_mu.py", line 199, in import_mu
if not mu.read(filepath):
File "C:\Users\HunKr\AppData\Roaming\Blender Foundation\Blender\2.91\scripts\addons\io_object_mu\mu.py", line 1181, in read
self.file = open(filepath, "rb")
TypeError: expected str, bytes or os.PathLike object, not NoneType
location: <unknown location>:-1
I've seen that someone has had this issue and they've posted what they did to fix it but it's not too clear what they did to fix it.