diff --git a/tools/update-rule-types.js b/tools/update-rule-types.js
index 352a0d8e336..3a20092a4eb 100644
--- a/tools/update-rule-types.js
+++ b/tools/update-rule-types.js
@@ -27,7 +27,7 @@ module.exports = (fileInfo, api) => {
 
         // if there's no properties, just exit
         if (!metaNode.value.properties) {
-            return; 
+            return null;
         }
 
         const typeNode = metaNode.value.properties.find(node => node.key.name === "type");