[STDERR] Uncaught PHP Exception TypeError: "Drupal\Core\Utility\ThemeRegistry::getGlobalPreprocess(): Return value must be of type array, null returned" at /home/user/domains/site.nl/public_html/core/lib/Drupal/Core/Utility/ThemeRegistry.php line 193

Based on broken theme registry cache

[public_html]$ ../vendor/drush/drush/drush cr