There seems to be an extra empty channel that wasn't originally there

[uep]

Yep, see here:

Error: reading symbolic link '/nix/var/nix/profiles/per-user/root/channels/"': No such file or directory

This is a bug, already fixed, see https://github.com/NixOS/nixpkgs/pull/264608 Edit: Turns out another PR is necessary to completely fix it: