Undefined index: Aluno

mesmo o codigo estando correcto ele apresenta o erro:

 Undefined index: Aluno in /Users/roquelaecio/Documents/aluraPHP/Doctrine-Parte01/vendor/doctrine/orm/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php on line 1779

Notice: Undefined index: Aluno in /Users/roquelaecio/Documents/aluraPHP/Doctrine-Parte01/vendor/doctrine/orm/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php on line 1779
PHP Notice:  Trying to access array offset on value of type null in /Users/roquelaecio/Documents/aluraPHP/Doctrine-Parte01/vendor/doctrine/orm/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php on line 1783

Codigo abaixo;

<?php

use Alura\Doctrine\Entity\Aluno;
use Alura\Doctrine\Entity\Telefone;
use Alura\Doctrine\Helper\EntityManagerFactory;

require_once __DIR__ . '/../vendor/autoload.php';

$entityManagerFactory = new EntityManagerFactory();
$entityManager = $entityManagerFactory->getEntityManager();

$alunoRepository = $entityManager->getRepository(Aluno::class);

/**
 * @var Aluno[] $alunoList
 */
$alunoList = $alunoRepository->findAll();

foreach ($alunoList as $aluno) {
    $telefones = $aluno
        ->getTelefones()
        ->map(function (Telefone $telefone) {
            return $telefone->getNumero();
        })
        ->toArray();

    echo "Id: {$aluno->getId()}\nNome: {$aluno->getNome()}\n\n";
    echo "Telefones: " . implode(',', $telefones);
}