error:
       … while calling the 'head' builtin
         at «github:NixOS/nixpkgs/8c3cede7ddc26bd659d2d383b5610efbd2c7a16e?narHash=sha256-rppURzHviaQN131F%2BnLiLdGfcb0uCd9gGP0E5%2Biw9MI%3D»/lib/attrsets.nix:1712:13:
         1711|           if length values == 1 || pred here (elemAt values 1) (head values) then
         1712|             head values
             |             ^
         1713|           else

       … while evaluating the attribute 'optionalValue.value'
         at «github:NixOS/nixpkgs/8c3cede7ddc26bd659d2d383b5610efbd2c7a16e?narHash=sha256-rppURzHviaQN131F%2BnLiLdGfcb0uCd9gGP0E5%2Biw9MI%3D»/lib/modules.nix:1332:5:
         1331|
         1332|     optionalValue = if isDefined then { value = mergedValue; } else { };
             |     ^
         1333|   };

       … while evaluating definitions from `/nix/store/sdywslbm666h9iiald96x4kxzhdr5pmp-source/lib/make-disk-image.nix':

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

       … while evaluating definitions from `/nix/store/kxf3k5sdq5cbs13sm9w109p5m9lyzh7x-source/nixos/modules/system/activation/top-level.nix':

       … while evaluating the option `assertions':

       … while evaluating definitions from `/nix/store/sdywslbm666h9iiald96x4kxzhdr5pmp-source/module.nix':

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

       error: attribute 'assertions' missing
       at /var/lib/nixbot/worktrees/148-ce162c78ae82-e91c57a5/module.nix:247:7:
          246|     assertions = lib.mkMerge [
          247|       cfg.devices._config.assertions
             |       ^
          248|       [