NixConfigurator: set default for services/schedulers/builders

Author: Mic92

buildbot_nix/buildbot_nix/__init__.py

@@ -1290,6 +1290,9 @@ def configure(self, config: dict[str, Any]) -> None:
         config.setdefault("secretsProviders", [])
         config.setdefault("www", {})
         config.setdefault("workers", [])
+        config.setdefault("services", [])
+        config.setdefault("schedulers", [])
+        config.setdefault("builders", [])
 
         worker_names = []
         for w in self.config.nix_worker_secrets().workers: