error:
       … while evaluating the attribute 'optionalValue.value'
         at «github:nixos/nixpkgs/f13ff45afd1bb73e640eaa08a7066dbed07e3238?narHash=sha256-zDSUbpoeo/9ZmD2%2BwXnzxoo1%2BuhL8vxc0b8yuYMKYq0%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/f13ff45afd1bb73e640eaa08a7066dbed07e3238?narHash=sha256-zDSUbpoeo/9ZmD2%2BwXnzxoo1%2BuhL8vxc0b8yuYMKYq0%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/fdxcjv332yd3lwgmy460n2119rbgwr44-source/parts/ci.nix, via option perSystem':

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

       … while evaluating definitions from `/nix/store/cc7ff4ysismx0c3778v8gc6b14plrz3z-source/nixos/modules/system/activation/top-level.nix':

       … while evaluating the option `assertions':

       … while evaluating definitions from `/nix/store/fdxcjv332yd3lwgmy460n2119rbgwr44-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/cc7ff4ysismx0c3778v8gc6b14plrz3z-source/nixos/modules/services/hardware/watt.nix' is already declared in `/nix/store/fdxcjv332yd3lwgmy460n2119rbgwr44-source/modules/programs/watt'.