Unable to install following NixOS Flakes Installation

[RashiqAzhan]

nixos-rebuild gives the following error.

building the system configuration...
error:
       … while calling the 'head' builtin

         at /nix/store/2lagifgqw760xch048spv2a0v46ya1vb-source/lib/attrsets.nix:922:11:

          921|         || pred here (elemAt values 1) (head values) then
          922|           head values
             |           ^
          923|         else

       … while evaluating the attribute 'value'

         at /nix/store/2lagifgqw760xch048spv2a0v46ya1vb-source/lib/modules.nix:807:9:

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

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

       error: undefined variable 'inputs'

       at /nix/store/4cjs18pa10jginiv2kzh5fy8bcxsdf52-source/configuration.nix:122:5:

          122|     inputs.nixos-conf-editor.packages.${system}.nixos-conf-editor
             |     ^
          123|   ];

I understood from error: undefined variable 'inputs' that inputs is undefined but where should this definition be and how to define it? Thank you for the any help that you can provide.

[pinkcreeper100]

@RashiqAzhan have you added inputs to the attribute set at the top of the file?

like this:

{
  config,
  pkgs,
  lib,
  inputs,
  ...
}: