From c9c98b403c913bb0d68fc0065ba191e8038de4e4 Mon Sep 17 00:00:00 2001
From: Jan Jakes <jan.jakes@automattic.com>
Date: Thu, 22 Sep 2022 15:26:31 +0200
Subject: [PATCH] Fix possible undefined index access

[MAILPOET-4629]
---
 mailpoet/lib/Automation/Engine/Control/StepHandler.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mailpoet/lib/Automation/Engine/Control/StepHandler.php b/mailpoet/lib/Automation/Engine/Control/StepHandler.php
index 53c2e18b64..be58a167de 100644
--- a/mailpoet/lib/Automation/Engine/Control/StepHandler.php
+++ b/mailpoet/lib/Automation/Engine/Control/StepHandler.php
@@ -181,7 +181,7 @@ class StepHandler {
   private function getSubjectEntries(WorkflowRun $workflowRun, array $requiredSubjectKeys): array {
     $subjectDataMap = [];
     foreach ($workflowRun->getSubjects() as $data) {
-      $subjectDataMap[$data->getKey()] = array_merge($subjectDataMap[$data->getKey()], [$data]);
+      $subjectDataMap[$data->getKey()] = array_merge($subjectDataMap[$data->getKey()] ?? [], [$data]);
     }
 
     $subjectEntries = [];