Installation through configuration.nix fails

[BlueFox1616]

the error : error: … while calling the 'head' builtin

     at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/attrsets.nix:1575:11:

     1574|         || pred here (elemAt values 1) (head values) then
     1575|           head values
         |           ^
     1576|         else

   … while evaluating the attribute 'value'

     at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:809:9:

      808|     in warnDeprecation opt //
      809|       { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
         |         ^
      810|         inherit (res.defsFinal') highestPrio;

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

   error: attempt to call something which is not a function but a set

   at /etc/nixos/configuration.nix:16:23:

       15| let
       16|   nixos-conf-editor = import (pkgs.fetchFromGitHub {
         |                       ^
       17|     owner = "snowfallorg";