From what I can see `lxd-unwrapped-lts` does not define `ui` attribute.
As a result `lxd.ui` fails the eval as:
$ nix build --no-link -f. lxd.ui
trace: warning: lxd has been renamed to lxd-lts
error: attribute 'ui' missing
at pkgs/by-name/lx/lxd-lts/package.nix:144:39:
143| passthru = {
144| inherit (lxd-unwrapped-lts) tests ui;
| ^
145| };
Did you mean one of go or out?