Index: Classes/Domain/Repository/PostRepository.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/Classes/Domain/Repository/PostRepository.php b/Classes/Domain/Repository/PostRepository.php
--- a/Classes/Domain/Repository/PostRepository.php	
+++ b/Classes/Domain/Repository/PostRepository.php	
@@ -414,7 +414,7 @@
 
     protected function getStoragePidsFromTypoScript(): array
     {
-        return GeneralUtility::intExplode(',', $this->settings['persistence']['storagePid']);
+        return GeneralUtility::intExplode(',', (string) $this->settings['persistence']['storagePid']);
     }
 
     /**