error:
       … while evaluating the attribute 'optionalValue.value'
         at «github:nixos/nixpkgs/0e251e24a4f24e036a084b6b4b2d2491af4167f4?narHash=sha256-yNJd40f11EzXBjSByCB7IPpeFFAdeoSKKM67dGkfFoU%3D»/lib/modules.nix:1312:5:
         1311|
         1312|     optionalValue = if isDefined then { value = mergedValue; } else { };
             |     ^
         1313|   };

       … while evaluating a branch condition
         at «github:nixos/nixpkgs/0e251e24a4f24e036a084b6b4b2d2491af4167f4?narHash=sha256-yNJd40f11EzXBjSByCB7IPpeFFAdeoSKKM67dGkfFoU%3D»/lib/modules.nix:1312:21:
         1311|
         1312|     optionalValue = if isDefined then { value = mergedValue; } else { };
             |                     ^
         1313|   };

       … while evaluating definitions from `/nix/store/lrxvs4l9bqbgjfz7w9bkfg5zqq442jxc-source/modules/transposition.nix':

       … while evaluating definitions from `/nix/store/l15gdcmzfrdmm7zmcmh76syv9frllhpr-source/parts/ci.nix, via option perSystem':

       … while evaluating the option `system.build.toplevel':

       … while evaluating definitions from `/nix/store/31w94yhfpllma9jnlgavjkzsfs548ijx-source/nixos/modules/system/activation/top-level.nix':

       … while evaluating the option `assertions':

       … while evaluating definitions from `/nix/store/l15gdcmzfrdmm7zmcmh76syv9frllhpr-source/modules/programs/watt':

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

       error: The option `services.watt.enable' in `/nix/store/31w94yhfpllma9jnlgavjkzsfs548ijx-source/nixos/modules/services/hardware/watt.nix' is already declared in `/nix/store/l15gdcmzfrdmm7zmcmh76syv9frllhpr-source/modules/programs/watt'.