502 Bad Gateway in $app->mount()

how to catch controller error and return exception i only got 502 bad gateway if i put intended error on my controller and no response in php56 and phalcon 2.0.x is working find but in PHP7 and Phalcon 3.0 i got 502 bad gateway please help thanks

        <?php

        namespace Controllers;

        class UsersController extends BaseController
        {
            asdasdasd <------- some intended error
            public function index() 
            {

            }

        }

        $test = new Phalcon\Mvc\Micro\Collection();
        $test->setHandler('Api\Controllers\TestController', true);
        $test->get('/','index');
        $app->mount($test);  // i got 502 bad gateway here how to catch error