<?php

namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\Routing\Annotation\Route;
use Symfony\Component\Serializer\Normalizer\DateTimeNormalizer;
use Symfony\Component\Serializer\SerializerInterface;

class DateTimeNormalizerErrorController extends AbstractController
{
    #[Route('/normalizer-bug-example', name: 'normalizer_bug_example')]
    public function __invoke(SerializerInterface $serializer): JsonResponse
    {
        $data = '{"exampleDate":1685716333}';  // Use timestamp to create DateTime
        // $data = '{"exampleDate":"13-05-2023"}';  // When using string value - everything works as expected

        // Throws NotNormalizableValueException
        $triggerErrorObject = $serializer->deserialize($data, ExampleEntity::class, 'json', [
            DateTimeNormalizer::FORMAT_KEY => 'U',  // When using string value - change the format to 'd-m-Y'
        ]);

        // dd($triggerErrorObject->getExampleDate());  // When using string value - this dumps a normal DateTime object

        return new JsonResponse($data, 200, [], true);
    }
}

class ExampleEntity
{
    private \DateTime $exampleDate;

    public function getExampleDate(): \DateTimeInterface
    {
        return $this->exampleDate;
    }

    public function setExampleDate(\DateTime $exampleDate): void
    {
        $this->exampleDate = $exampleDate;
    }
}

-       if (null === $data || (\is_string($data) && '' === trim($data))) {
+       if (null === $data || !\is_string($data) || '' === trim($data)) {