fix(post-renderer): fix null value validation panic in annotations an…

…d labels

Signed-off-by: Timofey Kirillov <timofey.kirillov@flant.com>

pkg/deploy/helm/extra_annotations_and_labels_post_renderer.go

@@ -147,7 +147,12 @@ func validateStringNode(node *yaml_v3.Node) error {
 		return fmt.Errorf("unable to decode value %q: %w", node.Value, err)
 	}
 	if _, ok := v.(string); !ok {
-		return fmt.Errorf("invalid node %q: expected string, got %s", node.Value, reflect.TypeOf(v).String())
+		typeOf := reflect.TypeOf(v)
+		if typeOf != nil {
+			return fmt.Errorf("invalid node %q: expected string, got %s", node.Value, reflect.TypeOf(v).String())
+		} else {
+			return fmt.Errorf("invalid node %q: expected string, got null value", node.Value)
+		}
 	}
 	return nil
 }