NixOS download fails

[Propfend]

nix-shell -p emmylua-ls

error:
       … while calling the 'derivationStrict' builtin
         at <nix/derivation-internal.nix>:37:12:
           36|
           37|   strict = derivationStrict drvAttrs;
             |            ^
           38|

       … while evaluating derivation 'shell'
         whose name attribute is located at /nix/store/7swmjsxz9m2gamk8q5m0m2byb2gq35v5-source/pkgs/stdenv/generic/make-derivation.nix:480:13

       … while evaluating attribute 'buildInputs' of derivation 'shell'
         at /nix/store/7swmjsxz9m2gamk8q5m0m2byb2gq35v5-source/pkgs/stdenv/generic/make-derivation.nix:535:13:
          534|             depsHostHost = elemAt (elemAt dependencies 1) 0;
          535|             buildInputs = elemAt (elemAt dependencies 1) 1;
             |             ^
          536|             depsTargetTarget = elemAt (elemAt dependencies 2) 0;

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: undefined variable 'emmylua-ls'
       at «string»:1:107:
            1| {...}@args: with import <nixpkgs> args; (pkgs.runCommandCC or pkgs.runCommand) "shell" { buildInputs = [ (emmylua-ls) ]; } ""

[bew]

You didn't give much information, for example which nixpkgs channel / branch are you on? This package is only available starting on the 25.11 release