set null metadata as empty (#1781)

Author: lukmzig

src/Metadata/Patcher/Adapter/CustomMetadataAdapter.php

@@ -95,7 +95,7 @@ public function patch(ElementInterface $element, array $data, UserInterface $use
         ];
 
         if (!empty($patchedMetadata)) {
-            $element->setMetadata($patchedMetadata);
+            $element->setMetadata($this->dataResolverService->prepareData($patchedMetadata));
         }
     }
 

src/Metadata/Service/DataResolverServiceInterface.php

@@ -21,6 +21,8 @@
  */
 interface DataResolverServiceInterface
 {
+    public function prepareData(array $customMetadata): array;
+
     /**
      * @throws InvalidArgumentException
      */

src/Metadata/Service/DataResolverServiceService.php

@@ -25,6 +25,15 @@ public function __construct(private DataAdapterServiceInterface $dataAdapterServ
     {
     }
 
+    public function prepareData(array $customMetadata): array
+    {
+        foreach ($customMetadata as $key => $metadata) {
+            $customMetadata[$key]['data'] = $metadata['data'] ?? '';
+        }
+
+        return $customMetadata;
+    }
+
     /**
      * {@inheritdoc}
      */

src/Metadata/Updater/Adapter/CustomMetadataAdapter.php

@@ -52,7 +52,7 @@ public function update(ElementInterface $element, array $data): void
 
         $this->eventDispatcher->dispatch($metadataEvent, CustomMetadataEvent::EVENT_NAME);
 
-        $element->setMetadata($metadataEvent->getCustomMetadata());
+        $element->setMetadata($this->dataResolverService->prepareData($metadataEvent->getCustomMetadata()));
     }
 
     public function getIndexKey(): string