Issue #2574095 by marcingy: File upload and entity autocomplete results in fatal

core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/EntityReferenceAutocompleteWidget.php

@@ -120,7 +120,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
    * {@inheritdoc}
    */
   public function errorElement(array $element, ConstraintViolationInterface $error, array $form, FormStateInterface $form_state) {
-    return $element['target_id'];
+    return isset($element['target_id']) ? $element['target_id'] : FALSE;
   }
 
   /**

core/modules/entity_reference/src/Tests/EntityReferenceFileUploadTest.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\entity_reference\Tests\EntityReferenceFileUploadTest.
+ */
+
+namespace Drupal\entity_reference\Tests;
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests an autocomplete widget with file upload.
+ *
+ * @group entity_reference
+ */
+class EntityReferenceFileUploadTest extends WebTestBase {
+
+  public static $modules = array('entity_reference', 'node', 'file');
+
+  /**
+   * The name of a content type that will reference $referencedType.
+   *
+   * @var string
+   */
+  protected $referencingType;
+
+  /**
+   * The name of a content type that will be referenced by $referencingType.
+   *
+   * @var string
+   */
+  protected $referencedType;
+
+  /**
+   * Node id.
+   *
+   * @var integer
+   */
+  protected $nodeId;
+
+  protected function setUp() {
+    parent::setUp();
+
+    // Create "referencing" and "referenced" node types.
+    $referencing = $this->drupalCreateContentType();
+    $this->referencingType = $referencing->id();
+
+    $referenced = $this->drupalCreateContentType();
+    $this->referencedType = $referenced->id();
+    $this->nodeId = $this->drupalCreateNode(array('type' => $referenced->id()))->id();
+
+    entity_create('field_storage_config', array(
+      'field_name' => 'test_field',
+      'entity_type' => 'node',
+      'translatable' => FALSE,
+      'entity_types' => array(),
+      'settings' => array(
+        'target_type' => 'node',
+      ),
+      'type' => 'entity_reference',
+      'cardinality' => FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED,
+    ))->save();
+
+    entity_create('field_config', array(
+      'label' => 'Entity reference field',
+      'field_name' => 'test_field',
+      'entity_type' => 'node',
+      'required' => TRUE,
+      'bundle' => $referencing->id(),
+      'settings' => array(
+        'handler' => 'default',
+        'handler_settings' => array(
+          // Reference a single vocabulary.
+          'target_bundles' => array(
+            $referenced->id(),
+          ),
+        ),
+      ),
+    ))->save();
+
+
+    // Create a file field.
+    $file_field_name = 'file_field';
+    $field_storage = entity_create('field_storage_config', array(
+      'field_name' => $file_field_name,
+      'entity_type' => 'node',
+      'type' => 'file'
+    ));
+    $field_storage->save();
+    entity_create('field_config', array(
+      'entity_type' => 'node',
+      'field_storage' => $field_storage,
+      'bundle' => $referencing->id(),
+      'label' => $this->randomMachineName() . '_label',
+    ))->save();
+
+    entity_get_display('node', $referencing->id(), 'default')
+      ->setComponent('test_field')
+      ->setComponent($file_field_name)
+      ->save();
+    entity_get_form_display('node', $referencing->id(), 'default')
+      ->setComponent('test_field', array(
+        'type' => 'entity_reference_autocomplete',
+      ))
+      ->setComponent($file_field_name, array(
+         'type' => 'file_generic',
+      ))
+      ->save();
+  }
+
+  /**
+   * Tests that the autocomplete input element does not cause ajax fatal.
+   */
+  public function testFileUpload() {
+    $user1 = $this->drupalCreateUser(array('access content', "create $this->referencingType content"));
+    $this->drupalLogin($user1);
+
+    $test_file = current($this->drupalGetTestFiles('text'));
+    $edit['files[file_field_0]'] = drupal_realpath($test_file->uri);
+    $this->drupalPostForm('node/add/' . $this->referencingType, $edit, 'Upload');
+    $this->assertResponse(200);
+    $edit = array(
+      'title[0][value]' => $this->randomMachineName(),
+      'test_field[0][target_id]' => $this->nodeId,
+    );
+    $this->drupalPostForm(NULL, $edit, 'Save');
+    $this->assertResponse(200);
+  }
+}