From 277648b81cb49cfd1449bc876f874c2421e97af2 Mon Sep 17 00:00:00 2001
From: "Thomas A. Hirsch" <thomas.hirsch@vema-eg.de>
Date: Tue, 18 Jan 2022 13:59:02 +0100
Subject: [PATCH] Cherry-picked from da76d927ed77fb6b3cb8345b83776712d0778e55
 Co-Authored-By: Thomas BACCELLI <tbaccelli@gmail.com>

---
 libs/sysplugins/smarty_internal_cacheresource_file.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libs/sysplugins/smarty_internal_cacheresource_file.php b/libs/sysplugins/smarty_internal_cacheresource_file.php
index abed98d8..c77ae9e1 100644
--- a/libs/sysplugins/smarty_internal_cacheresource_file.php
+++ b/libs/sysplugins/smarty_internal_cacheresource_file.php
@@ -196,8 +196,8 @@ class Smarty_Internal_CacheResource_File extends Smarty_CacheResource
      */
     public function hasLock(Smarty $smarty, Smarty_Template_Cached $cached)
     {
-        clearstatcache(true, $cached->lock_id);
-        if (is_file($cached->lock_id)) {
+        clearstatcache(true, $cached->lock_id ?? '');
+        if (null !== $cached->lock_id && is_file($cached->lock_id)) {
             $t = filemtime($cached->lock_id);
             return $t && (time() - $t < $smarty->locking_timeout);
         } else {