Post data not rendering after submitting form within the contact page

<?php
// require Slim
require 'vendor/autoload.php';
// Set time zone
date_default_timezone_set('America/Los_Angeles');

//slim-views is required for Twig
//see https://github.com/slimphp/Slim-Views
//must install via composer
$app = new \Slim\Slim(array(
    'view' => new \Slim\Views\Twig()
));

$view = $app->view();
$view->parserOptions = array(
    'debug' => true
);

//the code below enables us to use the helpers below
//urlFor siteUrl baseUrl currentUrl
//documentation at https://github.com/slimphp/Slim-Views
$view->parserExtensions = array(
    new \Slim\Views\TwigExtension(),
);

$app->get('/', function() use($app) {
    $app->render("about.twig");
})->name('home');

$app->get('/contact', function() use($app) {
    $app->render("contact.twig");
})->name('contact');

$app->post('/contact', function() use($app){
    $name = $app->request->post('name');
    $email = $app->request->post('email');
    $msg = $app->request->post('msg');

    if(!empty($name) && !empty($email) && !empty($msg)) {
        $cleanName = filter_var($name, FILTER_SANITIZE_STRING);
        $cleanEmail = filter_var($email, FILTER_SANITIZE_EMAIL);
        $cleanMsg = filter_var($msg, FILTER_SANITIZE_STRING);
    } else {
        //message the user there was a problem
        $app->redirect('/contact');
    }


    $transport = Swift_SendmailTransport::newInstance('/usr/sbin/sendmail -bs');
    $mailer = \Swift_Mailer::newInstance($transport);

    $message = \Swift_Message::newInstance();
    $message->setSubject('Email from Our Website');
    $message->setFrom(array(
        $cleanEmail => $cleanName
    ));

    $message->setTo(array('teds@biblewordstudy.net'));
    $message->setBody($cleanMsg);



    $result = $mailer->send($message);

    if($result>0) {
        // send a message that says thank you
        $app->redirect('/');
    } else {
        // send a message to the user that teh message failed to send
        // log that there was an error
        $app->redirect('/contact');
    }
});

$app->run();