Fixed null deprecation in UnserializeArray.php

app/code/core/Mage/Core/Helper/UnserializeArray.php

@@ -26,11 +26,13 @@ class Mage_Core_Helper_UnserializeArray
      * @param string $str
      * @return array
      * @throws Exception
+     * @SuppressWarnings("PHPMD.ErrorControlOperator")
      */
     public function unserialize($str)
     {
         try {
-            $result = unserialize($str, ['allowed_classes' => false]);
+            $str = is_null($str) ? '' : $str;
+            $result = @unserialize($str, ['allowed_classes' => false]);
             if ($result === false && $str !== serialize(false)) {
                 throw new Exception('Error unserializing data.');
             }

tests/unit/Mage/Core/Helper/UnserializeArrayTest.php

@@ -59,7 +59,7 @@ public function provideUnserialize(): Generator
             '',
         ];
         yield 'random string' => [
-            'unserialize(): Error at offset 0 of 3 bytes',
+            'Error unserializing data.',
             'abc',
         ];
         yield 'valid' => [