Wrap the networking_local.nix, because of the error.

nix-system-configs/modules/local/networking_local.nix

@@ -4,6 +4,7 @@
   lib,
   ...
 }: {
+  config = {
     # Some programs need SUID wrappers, can be configured further or are
     # started in user sessions.
     # programs.mtr.enable = true;
@@ -42,4 +43,5 @@
 
     # Explicitly set DNS
     networking.nameservers = ["10.1.1.2"]; # PiHole DNS
+  };
 }