NinjaCoder69试试看：

use App\Entity\Lessen;
use Proxies\__CG__\App\Entity\User;
use Symfony\Bridge\Doctrine\Form\Type\EntityType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;

class LessenType extends AbstractType
{
    private $tokenStorage;

    public function __construct(TokenStorageInterface $tokenStorage)
    {
        $this->tokenStorage = $tokenStorage;
    }
    public function buildForm(FormBuilderInterface $builder, array $options): void
    {
        $user = $this->tokenStorage->getToken()->getUser();


        $builder
            // STATUS EERST OPTIONEEL MAKEN IN DB (Als het staat op tecnhnisch ontwerp docenten)
//            ->add('status', null, [
//                'empty_data' => "\xC2\xA0",
//            ])

            ->add('ophaal_locatie')
            ->add('lesdoel')
            ->add('naam_leerling')
            ->add('naam_instructeur', null, [
                'data' => $user->getEmail(),
                'label' => false,
                'attr' => [
                    'class' => 'my-custom-class',
                    'style' => 'display: none;',
                ],
            ])

            ->add('datum')
            ->add('prijs')
            ->add('Leerling', EntityType::class, [
                'class' => User::class, 
                'choice_label' => 'username', 
            ])
        ;
    }

->add('Leerling', EntityType::class, [
    'class' => User::class, 
    'choice_label' => 'username', 
])