Fail fast to avoid dealing with null

fail-fast.php

<?php
declare(strict_types=1);

class UserException extends Exception { }

class Application
{
    ...

    public function getUser() : User
    {
        if (empty($this->identity)) {
            throw new UserException('User is not authenticated.');
        }
        return $this->identity;
    }
}

try {
    echo "Olá, " . $app->getUser()->name, "!";
} catch (UserException $e) {
    echo "Olá!";
}