ooops, nixos cannot compute

nixos/default.nix

@@ -34,8 +34,10 @@ in with lib; {
       '';
     };
 
-    users.users."${cfg.user}".packages = [ appvm ];
-    users.users."${cfg.user}".extraGroups = [ "libvirtd" ];
+    users.users."${cfg.user}" = {
+      packages = [ appvm ];
+      extraGroups = [ "libvirtd" ];
+    };
 
   };