Move data-component-id to TwigExtension::normalizeProps()

src/Element/ComponentElementAlter.php

@@ -36,11 +36,6 @@ class ComponentElementAlter implements TrustedCallbackInterface {
    */
   public function alter(array $element): array {
     $element = $this->normalizeSlots($element);
-    $component = $this->componentPluginManager->find($element['#component']);
-    // Attributes prop must never be empty, to avoid the processing of SDC's
-    // ComponentsTwigExtension::mergeAdditionalRenderContext() which is adding
-    // an Attribute PHP object before running the validator.
-    $element["#props"]["attributes"]['data-component-id'] = $component->getPluginId();
     $element = $this->processAttributesRenderProperty($element);
     return $element;
   }

src/Template/TwigExtension.php

@@ -123,9 +123,12 @@ class TwigExtension extends AbstractExtension {
   public function normalizeProps(array &$context, string $component_id): void {
     $component = $this->componentManager->find($component_id);
     $props = $component->metadata->schema['properties'] ?? [];
-    if (!isset($context['attributes'])) {
-      $context['attributes'] = [];
-    }
+    // Attributes prop must never be empty, to avoid the processing of SDC's
+    // ComponentsTwigExtension::mergeAdditionalRenderContext() which is adding
+    // an Attribute PHP object before running the validator.
+    // Attribute PHP object are casted as string by the validator and trigger
+    // '[attributes] String value found, but an object is required' error.
+    $context['attributes']['data-component-id'] = $component->getPluginId();
     foreach ($context as $variable => $value) {
       if (isset($component->metadata->slots[$variable])) {
         $context[$variable] = SlotPropType::normalize($value);