#Issue 3504217:Fix php fatal error.

Closes #3504217

src/Form/BaseFormFields.php

@@ -4,6 +4,7 @@ namespace Drupal\migrate_wizard\Form;
 
 use Drupal\Core\StringTranslation\TranslatableMarkup;
 use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Config\TypedConfigManager;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -136,7 +137,7 @@ abstract class BaseFormFields extends ConfigFormBase {
       MWManageDataService $mw_manage_data_service,
       EntityTypeManagerInterface $entity_type_manager,
       MWManageFormService $manage_form_service,
-      protected $typedConfigManager = NULL) {
+      TypedConfigManager $typedConfigManager) {
 
     parent::__construct($config_factory, $typedConfigManager);
     $this->mwManageDataService = $mw_manage_data_service;