3362808 - Skip node without id

Closes #3362808

src/Plugin/Field/FieldFormatter/JsonLdHeadFormatter.php

@@ -26,6 +26,11 @@ class JsonLdHeadFormatter extends FormatterBase {
     $elements = ['#attached' => ['html_head' => []]];
     $entity = $items->getEntity();
 
+    // Skip adding jsonld schema for non saved yet entity.
+    if ($entity->isNew()) {
+      return [];
+    }
+
     // When there is no item, default to the configured values without any
     // overrides. See JsonLdItem::isEmpty().
     if (count($items) === 0) {