Notice: Undefined index: #item in user_user_view_alter()

Problem/Motivation

Notice: Undefined index: #item in user_user_view_alter() (line 409 of /Users/jungle/repo/drupal/web/core/modules/user/user.module) #0 

The line 409 of the file core/modules/user/user.module:

    $item = $build['user_picture'][$key]['#item'];

The background is that I was Implementing the avatar_field_formatter module, found that the #item in user_user_view_alter() dose not exist. As a custom image formatter, what the module does is if the image is empty, display an avatar letter generated instead.

The user_user_view_alter implementation in core assuming that the returned non-empty render array of user picture's field formatter always has #item key(s). Considering another use case, for an empty user picture, one wants to display a plain text: "No avatar" by using a custom field formatter. It may throw the same error too.

The whole function relevant:

/**
 * Implements hook_ENTITY_TYPE_view_alter() for user entities.
 *
 * This function adds a default alt tag to the user_picture field to maintain
 * accessibility.
 */
function user_user_view_alter(array &$build, UserInterface $account, EntityViewDisplayInterface $display) {
  if (user_picture_enabled() && !empty($build['user_picture'])) {
    foreach (Element::children($build['user_picture']) as $key) {
      $item = $build['user_picture'][$key]['#item'];
      if (!$item->get('alt')->getValue()) {
        $item->get('alt')->setValue(\Drupal::translation()->translate('Profile picture for user @username', ['@username' => $account->getAccountName()]));
      }
    }
  }
}

Steps to reproduce

1. Apply patch: 3072305-11-test-only.patch in #11
2. Add $settings['extension_discovery_scan_tests'] = TRUE; to settings.php
3. Install Image test module (module machine name: image_module_test)
4. Login as user 1
5. Visit /admin/config/people/accounts/display
6. Select Dummy image formatter for Picture field
7. Visit /user/1, 500 error, reproduced.

Proposed resolution

Check the existence of #item first, and make sure it's an instance of ImageItem for further processing

+++ b/core/modules/user/user.module
@@ -416,9 +417,14 @@ function user_user_view(array &$build, UserInterface $account, EntityViewDisplay
     foreach (Element::children($build['user_picture']) as $key) {
+      if (!isset( $build['user_picture'][$key]['#item'])) {
+        continue;
+      }
       $item = $build['user_picture'][$key]['#item'];
-      if (!$item->get('alt')->getValue()) {
-        $item->get('alt')->setValue(\Drupal::translation()->translate('Profile picture for user @username', ['@username' => $account->getAccountName()]));
+      if ($item instanceof ImageItem) {
+        if (!$item->get('alt')->getValue()) {
+          $item->get('alt')->setValue(\Drupal::translation()->translate('Profile picture for user @username', ['@username' => $account->getAccountName()]));
+        }
       }

Remaining tasks

Needs review

How to test the patch manually

1. Apply patch: 3072305-11.patch in #11
2. Add $settings['extension_discovery_scan_tests'] = TRUE; to settings.php
3. Install Image test module (module machine name: image_module_test)
4. Login as user 1
5. Visit /admin/config/people/accounts/display
6. Select Dummy image formatter for Picture field
7. Visit /user/1, you should see text Dummy which provides by the Dummy image formatter in Image test module.

User interface changes

No

API changes

No

Data model changes

No