Fixed #196

Author: brandonkelly

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Release Notes for Element API
 
+## Unreleased
+
+- Fixed an error that occurred if no cache tags were registered by an endpoint’s element query. ([#196](https://github.com/craftcms/element-api/issues/196))
+
 ## 4.1.0 - 2024-03-14
 
 - Element API now requires Craft 4.3.0+ or 5.0.0+.

src/controllers/DefaultController.php

@@ -25,6 +25,7 @@
 use ReflectionFunction;
 use yii\base\InvalidConfigException;
 use yii\base\UserException;
+use yii\caching\TagDependency;
 use yii\web\HttpException;
 use yii\web\JsonResponseFormatter;
 use yii\web\Response;
@@ -234,6 +235,7 @@ public function actionIndex(string $pattern): Response
 
             /** @phpstan-ignore-next-line */
             [$dep, $maxDuration] = $elementsService->stopCollectingCacheInfo();
+            $dep ??= new TagDependency();
             $dep->tags[] = 'element-api';
 
             if ($maxDuration) {