A simple bandaid fix for the modern version of Fabric API (until fixed by modmuss50) that uses a single mixin targetting the 'net.fabricmc.fabric.impl.attachment.sync.AttachmentChange' class to simply discard attachment packets if the target is unknown instead of kicking the player (and usually requiring the player to rejoin the world a few times to despawn the problematic entity).
Currently this only seems to be an issue on modern versions of Fabric API and on versions 1.21.1+.
If you need this mod for other versions please let me know so I can release a fix for that version too!
This kick screen ^^ will no longer happen since the attachment packets get discarded instead of throwing this exception.
