Fatal error: Uncaught Error: Class "Drupal\Component\Diff\MappedDiff" not found in /home/www/drupal8/test/core/lib/Drupal/Component/Diff/WordLevelDiff.php:12 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Component/Diff/WordLevelDiff.php on line 12