diff -u b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
--- b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -189,7 +189,7 @@
         // If the entity has been saved and we're trying to set both the
         // target_id and the entity values with a non-null target ID, then the
         // value for target_id should match the ID of the entity value.
-        if (!$this->entity->isNew() && $values['target_id'] !== NULL && ($entity_id !== $values['target_id'])) {
+        if (!$this->entity->isNew() && $values['target_id'] !== NULL && ($entity_id != $values['target_id'])) {
           throw new \InvalidArgumentException('The target id and entity passed to the entity reference item do not match.');
         }
       }
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Form/FormState.php
+++ b/core/lib/Drupal/Core/Form/FormState.php
@@ -1163,7 +1163,8 @@ public function setFormObject(FormInterface $form_object) {
    * {@inheritdoc}
    */
   public function getFormObject() {
-    return $this->getBuildInfo()['callback_object'];
+    $build_info = $this->getBuildInfo();
+    return isset($build_info['callback_object']) ? $build_info['callback_object'] : NULL;
   }
 
   /**
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Form/FormStateInterface.php
+++ b/core/lib/Drupal/Core/Form/FormStateInterface.php
@@ -590,8 +590,8 @@ public function prepareCallback($callback);
   /**
    * Returns the form object that is responsible for building this form.
    *
-   * @return \Drupal\Core\Form\FormInterface
-   *   The form object.
+   * @return \Drupal\Core\Form\FormInterface|NULL
+   *   The form object or NULL if not set.
    */
   public function getFormObject();