From 1cad9caef9bd3f4efd74c102a962adf0d4c33507 Mon Sep 17 00:00:00 2001
From: Simon Schmidt <mfcsfs@googlemail.com>
Date: Wed, 15 May 2024 16:59:19 +0200
Subject: [PATCH] Fix error if no cache tags was registered

If no cache tags was registered, stopCollectingCacheInfo() returns [null, null]. If we try to assign another tag 'element-api' on it, we get the following error:
[Error] Attempt to modify property "tags" on null

This patch solves the problem.
---
 src/controllers/DefaultController.php | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/controllers/DefaultController.php b/src/controllers/DefaultController.php
index ea8c937..9a255be 100644
--- a/src/controllers/DefaultController.php
+++ b/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;
@@ -234,7 +235,14 @@ public function actionIndex(string $pattern): Response
 
             /** @phpstan-ignore-next-line */
             [$dep, $maxDuration] = $elementsService->stopCollectingCacheInfo();
-            $dep->tags[] = 'element-api';
+            
+            if (is_null($dep)) {
+                $dep = new TagDependency([
+                    'tags' => ['element-api'],
+                ]);
+            } else {
+                $dep->tags[] = 'element-api';
+            }
 
             if ($maxDuration) {
                 if ($expire !== null) {