Erreur (502 Bad gateway) ???

Voici mon code :

<?php require 'inc/header.php'; ?>

<?php
if(:empty($_POST)){

$errors = array();

if (empty($_POST['username'])|| :prog_match('/^[a-zA-Z0-9_]+$/', $_POST['username']))(
$errors['username'] = "Votre pseudo n'est pas valide (alphanumérique)";


}


if(empty($_POST['email']) || :filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)){
$errors['email'] = 'votre email n'est pas valide ;

{

if(empty($_POST['passeword'])|| $_POST)['passeword'] !=$_POST['passeword_confirm'] {
$errors['passeword']= "Vous devez rentrer un mot de passe


debug($errors),;
}
?>

<h1>S'inscrire</h1>

<form action=""method="post">

<div class="form-group"
<label for="">pseudo</label>
<input type="text" name="username" class="form-control" required/>
</div>


<div class="form-group"
<label for="">Email</label>
<input type="text" name="email" class="form-control" required/>
</div>



<div class="form-group"
<label for="">Mot de passe</label>
<input type="password" name="passeword" class="form-control" required/>
</div>

<div class="form-group"
<label for="">Confirmez votre Mot de passe</label>
<input type="password" name="passeword_confirm" required/>
</div

<button type="submit" class="btn btn-primary">M'inscrire</button>

</form>
<?php require 'inc/footer.php'; ?>

?>