nixos/amazon-image: fix eval

[wolfgangwalther]

The changes introduced in #377406 fail like this for me:

       error: attempt to call something which is not a function but a set: { _type = "if"; condition = «thunk»; content = «thunk»; }
       at [...]/nixos/modules/virtualisation/amazon-image.nix:31:23:
           30|
           31|     fileSystems."/" = mkIf (!cfg.zfs.enable) lib.mkDefault {
             |                       ^
           32|       device = "/dev/disk/by-label/nixos";

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[arianvp]

I wonder why this wasn't caught by nixpkgs-eval? Odd

[Guanran928]

Hit the same issue