Fatal error: Uncaught Error: Class "Drupal\Core\TypedData\Plugin\DataType\Map" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Field/FieldItemBase.php:20 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Field/FieldItemBase.php on line 20