Почему Fatal error: Allowed memory size of???

<?php

class BaseClass
{
    public function __construct(array $arguments = [])
    {
        foreach ($arguments as $property => $argument) {
            $this->{$property} = $argument;
        }
    }

    public function __call($method, $arguments)
    {
        if (isset($this->{$method}) /*&& is_callable($this->{$method})*/) {
            return $this->{$method}($arguments);
        } else {
            throw new Exception("Fatal error: Call to undefined method BaseClass::{$method}()");
        }
    }
}


class App extends BaseClass
{
    function hello()
    {
        echo "hello world";
    }
}

$app1 = new App();
$app1->hello();

$app2 = new BaseClass([
    'hello' => function () {
        echo "hello world";
    }
]);
$app2->hello();