error:
       … while calling anonymous lambda
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/attrsets.nix:1696:14:
         1695|         zipAttrsWith (
         1696|           n: values:
             |              ^
         1697|           let

       … while calling the 'head' builtin
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/attrsets.nix:1701:13:
         1700|           if length values == 1 || pred here (elemAt values 1) (head values) then
         1701|             head values
             |             ^
         1702|           else

       … while calling anonymous lambda
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/attrsets.nix:1193:17:
         1192|         mapAttrs (
         1193|           name: value:
             |                 ^
         1194|           if isAttrs value && cond value then recurse (path ++ [ name ]) value else f (path ++ [ name ]) value

       … from call site
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/attrsets.nix:1194:85:
         1193|           name: value:
         1194|           if isAttrs value && cond value then recurse (path ++ [ name ]) value else f (path ++ [ name ]) value
             |                                                                                     ^
         1195|         );

       … while calling anonymous lambda
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:275:71:
          274|           # For definitions that have an associated option
          275|           declaredConfig = mapAttrsRecursiveCond (v: !isOption v) (_: v: v.value) options;
             |                                                                       ^
          276|

       … while evaluating the attribute 'value'
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1118:7:
         1117|     // {
         1118|       value = addErrorContext "while evaluating the option `${showOption loc}':" value;
             |       ^
         1119|       inherit (res.defsFinal') highestPrio;

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

       … while evaluating the attribute 'mergedValue'
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1166:5:
         1165|     # Type-check the remaining definitions, and merge them. Or throw if no definitions.
         1166|     mergedValue =
             |     ^
         1167|       if isDefined then

       … while evaluating a branch condition
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1167:7:
         1166|     mergedValue =
         1167|       if isDefined then
             |       ^
         1168|         if type.merge ? v2 then

       … while evaluating the attribute 'values'
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1160:9:
         1159|       {
         1160|         values = defsSorted;
             |         ^
         1161|         inherit (defsFiltered) highestPrio;

       … while evaluating a branch condition
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1154:11:
         1153|           # Avoid sorting if we don't have to.
         1154|           if any (def: def.value._type or "" == "order") defsFiltered.values then
             |           ^
         1155|             sortProperties defsFiltered.values

       … while calling the 'any' builtin
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1154:14:
         1153|           # Avoid sorting if we don't have to.
         1154|           if any (def: def.value._type or "" == "order") defsFiltered.values then
             |              ^
         1155|             sortProperties defsFiltered.values

       … while evaluating the attribute 'values'
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1331:7:
         1330|     {
         1331|       values = concatMap (def: if getPrio def == highestPrio then [ (strip def) ] else [ ]) defs;
             |       ^
         1332|       inherit highestPrio;

       … while calling the 'concatMap' builtin
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1331:16:
         1330|     {
         1331|       values = concatMap (def: if getPrio def == highestPrio then [ (strip def) ] else [ ]) defs;
             |                ^
         1332|       inherit highestPrio;

       … while calling the 'concatMap' builtin
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1134:26:
         1133|         # Process mkMerge and mkIf properties.
         1134|         defsNormalized = concatMap (
             |                          ^
         1135|           m:

       … while calling anonymous lambda
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1135:11:
         1134|         defsNormalized = concatMap (
         1135|           m:
             |           ^
         1136|           map (

       … while calling the 'map' builtin
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1136:11:
         1135|           m:
         1136|           map (
             |           ^
         1137|             value:

       … while evaluating definitions from `/nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/nixos/modules/system/activation/top-level.nix':

       … from call site
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1145:80:
         1144|               }
         1145|           ) (addErrorContext "while evaluating definitions from `${m.file}':" (dischargeProperties m.value))
             |                                                                                ^
         1146|         ) defs;

       … while calling 'dischargeProperties'
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1282:5:
         1281|   dischargeProperties =
         1282|     def:
             |     ^
         1283|     if def._type or "" == "merge" then

       … while evaluating a branch condition
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:1283:5:
         1282|     def:
         1283|     if def._type or "" == "merge" then
             |     ^
         1284|       concatMap dischargeProperties def.contents

       … while evaluating the attribute 'value'
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/modules.nix:805:21:
          804|             inherit (module) file;
          805|             inherit value;
             |                     ^
          806|           }) module.config

       … from call site
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/nixos/modules/system/activation/top-level.nix:83:26:
           82|   # Handle assertions and warnings
           83|   baseSystemAssertWarn = lib.asserts.checkAssertWarn config.assertions config.warnings baseSystem;
             |                          ^
           84|

       … while calling 'checkAssertWarn'
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/asserts.nix:193:27:
          192|   checkAssertWarn =
          193|     assertions: warnings: val:
             |                           ^
          194|     let

       … while calling the 'throw' builtin
         at /nix/store/jc3mfa7ybzh32bkvdj5xiib1vkx8jy6x-source/lib/asserts.nix:198:7:
          197|     if failedAssertions != [ ] then
          198|       throw "\nFailed assertions:\n${concatStringsSep "\n" (map (x: "- ${x}") failedAssertions)}"
             |       ^
          199|     else

       error:
       Failed assertions:
       - Exactly one of users.users.user.isSystemUser and users.users.user.isNormalUser must be set.

       - users.users.user.group is unset. This used to default to
       nogroup, but this is unsafe. For example you can create a group
       for this user with:
       users.users.user.group = "user";
       users.groups.user = {};
Command 'nix --extra-experimental-features 'nix-command flakes' build --print-out-paths '/home/boxuser/haus#nixosConfigurations."box".config.system.build.toplevel' --show-trace --no-link' returned non-zero exit status 1.