Issue #3143087 by neclimdul, Kristen Pol: Define accessManager property for ModulesListForm

core/modules/system/src/Form/ModulesListForm.php

@@ -76,6 +76,13 @@ class ModulesListForm extends FormBase {
    */
   protected $moduleExtensionList;
 
+  /**
+   * The access manager.
+   *
+   * @var \Drupal\Core\Access\AccessManagerInterface
+   */
+  protected $accessManager;
+
   /**
    * {@inheritdoc}
    */