make use of 2.0.13 ExitCode class in console command

commands/HelloController.php

@@ -8,6 +8,7 @@
 namespace app\commands;
 
 use yii\console\Controller;
+use yii\console\ExitCode;
 
 /**
  * This command echoes the first argument that you have entered.
@@ -26,5 +27,7 @@ class HelloController extends Controller
     public function actionIndex($message = 'hello world')
     {
         echo $message . "\n";
+
+        return ExitCode::OK;
     }
 }