devenv reproduction - exit code

.envrc

#!/usr/bin/env bash
set -euo pipefail

# Docs: https://direnv.net/

if ! has nix_direnv_version || ! nix_direnv_version 2.3.0; then
    source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/2.3.0/direnvrc" "sha256-Dmd+j63L84wuzgyjITIfSxSD57Tx7v51DMxVZOsiUD8="
fi

nix_direnv_watch_file devenv.nix

if ! use flake . --impure; then
    echo "devenv could not be build. The devenv environment was not loaded. Make the necessary changes to devenv.nix and hit enter to try again." >&2
fi

devenv.nix

# Docs: https://devenv.sh/basics/
{ pkgs, ... }: {
  BROKEN
}

flake.nix

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05"; # or use /nixos-unstable to get latest packages, but maybe less caching
    systems.url = "github:nix-systems/default"; # (i) allows overriding systems easily, see https://github.com/nix-systems/nix-systems#consumer-usage
    devenv.url = "github:cachix/devenv";
  };

  outputs = { self, nixpkgs, devenv, systems, flake-parts, ... } @ inputs: (
    flake-parts.lib.mkFlake { inherit inputs; } {
      systems = (import systems);
      imports = [
        inputs.devenv.flakeModule
      ];
      perSystem = { config, self', inputs', pkgs, system, ... }: # perSystem docs: https://flake.parts/module-arguments.html#persystem-module-parameters
        let
          pkgs = nixpkgs.legacyPackages.${system};
        in
        {
          devenv.shells.default = (import ./devenv.nix { inherit pkgs inputs; });
        };
    }
  );

  nixConfig = {
    extra-substituters = [ "https://devenv.cachix.org" ];
    extra-trusted-public-keys = [ "devenv.cachix.org-1:w1cLUi8dv3hnoSPGAuibQv+f9TZLr6cv/Hm9XgU50cw=" ];
  };
}