error when 'nix flake check'

[unazikx]

❯ nix flake check
warning: unknown flake output 'debug'
trace: evaluation warning: Nixpkgs 26.05 will be the last release to support x86_64-darwin; see https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.05
error:
       … while checking flake output 'checks'

       … while checking the derivation 'checks.x86_64-linux."files/readme.md"'

       … while evaluating an expression to select 'drvPath' on it
         at «internal»:1:552:
       (stack trace truncated; use '--show-trace' to show the full trace)

       error: opening file '/nix/store/501lxp0c8chziirbx1df86bdym0iz48w-source/readme.md': No such file or directory

       note: trace involved the following derivations:
       derivation 'flake-file-check'

❯ eza -1
 lib
 machines
 modules
 persystem
 flake.lock
 flake.nix
 LICENSE
󰂺 README.md

{
  perSystem =
    {
      pkgs,
      ...
    }:
    {
      files = {
        files = [
          {
            path_ = "readme.md";
            drv =
              pkgs.writeText "README.md"
                # markdown
                ''
                  hello world
                '';
          }
        ];
      };
    };
}

what i do wrong?

[unazikx]

i made touch readme.md and added to git git add readme.md and got this

❯ nix flake check
warning: unknown flake output 'debug'
trace: evaluation warning: Nixpkgs 26.05 will be the last release to support x86_64-darwin; see https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.05
warning: unknown flake output 'allSystems'
warning: unknown flake output 'homeModules'
warning: unknown flake output 'diskoConfigurations'
warning: unknown flake output 'wrappers'
warning: unknown flake output 'wrapperModules'
error: builder for '/nix/store/mhag1k0bs1z3km2l5p6sdkbsk7fi4lxj-flake-file-check.drv' failed with exit code 1;
       last 4 log lines:
       > /nix/store/6kpmfdbq5xqmykp4sv50ylrr0lkxdkv4-README.md --- Text
       > 1    hello world
       >    1 
       >
       For full logs, run:
           nix log /nix/store/mhag1k0bs1z3km2l5p6sdkbsk7fi4lxj-flake-file-check.drv