inventory: don't loose string context of directory

checks/lib/test-inventory.nix

@@ -32,7 +32,7 @@ in
       nodes = flip mapAttrs serviceConfigs.machines (
         machineName: attrs: {
           imports = attrs.machineImports ++ [ self.nixosModules.clanCore ];
-          clan.core.settings.directory = toString config.inventory.directory;
+          clan.core.settings.directory = "${config.inventory.directory}";
           clan.core.settings.machine.name = machineName;
         }
       );

lib/build-clan/interface.nix

@@ -27,7 +27,7 @@ in
         else if v == null then
           throw "Please set either clan.self or clan.directory"
         else
-          builtins.toString v
+          "${v}"
       ) lib.types.path;
       default = builtins.toString self;
       defaultText = "Root directory of the flake";