Merge pull request #4082 from ocextension/patch-1

Update modification.php fix

upload/admin/controller/extension/modification.php

@@ -422,7 +422,7 @@ public function refresh($data = array()) {
 			$this->model_setting_setting->editSettingValue('config', 'config_maintenance', $maintenance);
 
 			// Do not return success message if refresh() was called with $data
-			if (!data['redirect']) {
+			if (!$data['redirect']) {
 				$this->session->data['success'] = $this->language->get('text_success');
 			}