diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php
index 4cff988..09e74f8 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php
@@ -29,7 +29,7 @@ class AuthorAutocompleteWidget extends RouteBasedAutocompleteWidget {
   public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, array &$form_state) {
     $element = parent::formElement($items, $delta, $element, $form, $form_state);
 
-    $entity = $element['#entity'];
+    $entity = $items->getEntity();
     $element['target_id']['#default_value'] = $entity->getOwner()->isAuthenticated() ? $entity->getOwner()->getUsername() : '';
 
     $user_config = \Drupal::config('user.settings');
diff --git a/core/modules/field/config/schema/field.schema.yml b/core/modules/field/config/schema/field.schema.yml
index 7018b5f..ca57b6a 100644
--- a/core/modules/field/config/schema/field.schema.yml
+++ b/core/modules/field/config/schema/field.schema.yml
@@ -291,3 +291,15 @@ entity_form_display.field.number:
         placeholder:
           type: label
           label: 'Placeholder'
+
+entity_form_display.field.timestamp:
+  type: entity_field_form_display_base
+  label: 'Timestamp default display format settings'
+  mapping:
+    settings:
+      type: mapping
+      label: 'Settings'
+      mapping:
+        use_request_time_on_empty:
+          type: boolean
+          label: 'Whether the current request time should be used if an empty value is submitted'
diff --git a/core/modules/node/src/Tests/PagePreviewTest.php b/core/modules/node/src/Tests/PagePreviewTest.php
index 4578352..a567932 100644
--- a/core/modules/node/src/Tests/PagePreviewTest.php
+++ b/core/modules/node/src/Tests/PagePreviewTest.php
@@ -207,7 +207,7 @@ function testPagePreviewWithRevisions() {
     $this->assertFieldByName($term_key, $edit[$term_key], 'Term field displayed.');
 
     // Check that the log field has the correct value.
-    $this->assertFieldByName('revision_log[0][value]', $edit['log[0][value]'], 'Revision Log field displayed.');
+    $this->assertFieldByName('revision_log[0][value]', $edit['revision_log[0][value]'], 'Revision Log field displayed.');
   }
 
 }