"multiworld:" included in save path when creating a new world, crashes due to invalid character for file system

[tehPete]

[18:25:52] [Server thread/INFO]: [STDERR]: net.minecraft.class_151: Non [a-z0-9/._-] character in path of location: multiworld:\"test\"
[18:25:52] [Server thread/INFO]: [STDERR]: 	at net.minecraft.class_2960.method_45137(class_2960.java:252)
[18:25:52] [Server thread/INFO]: [STDERR]: 	at net.minecraft.class_2960.<init>(class_2960.java:47)
[18:25:52] [Server thread/INFO]: [STDERR]: 	at net.minecraft.class_2960.<init>(class_2960.java:51)
[18:25:52] [Server thread/INFO]: [STDERR]: 	at net.minecraft.class_2960.<init>(class_2960.java:56)
[18:25:52] [Server thread/INFO]: [STDERR]: 	at me.isaiah.multiworld.fabric.FabricWorldCreator.create_world(FabricWorldCreator.java:36)
[18:25:52] [Server thread/INFO]: [STDERR]: 	at me.isaiah.multiworld.MultiworldMod.create_world(MultiworldMod.java:60)
[18:25:52] [Server thread/INFO]: [STDERR]: 	at me.isaiah.multiworld.command.CreateCommand.run(CreateCommand.java:57)
[18:25:52] [Server thread/INFO]: [STDERR]: 	at me.isaiah.multiworld.MultiworldMod.broadcast(MultiworldMod.java:204)
[18:25:52] [Server thread/INFO]: [STDERR]: 	at me.isaiah.multiworld.MultiworldMod.lambda$register_commands$2(MultiworldMod.java:116)

I tried forcing it with quotemarks - didn't work. Without, the path is 'multiworld:test'.
[e] This is on Fabric 1.20.1, using the latest test release