Error handling when misuse of find() with array values

[symfonyaml]

Bug Report

Q	A
BC Break	no
Version	2.18.x

Summary

Misuse of $em->find(...) with array as identifier.

Current behavior

$em->find(
    Test::class,
    ['id' => [1234]], // <----- Note the identifier is an array, which is wrong
);
// returns the following PHP warning :
// PHP Warning:  Array to string conversion in UnitOfWork.php on line 1560

How to reproduce

• Create a new directory

  mkdir ./reproduce-doctrine-bug
  cd ./reproduce-doctrine-bug

• Install the doctrine/orm and symfony/cache repos

  composer require doctrine/orm:^2.18 symfony/cache

• Create a Test entity

  mkdir Entity
  echo "<?php
  namespace App\Entity;
  use Doctrine\ORM\Mapping as ORM;
  #[ORM\Entity]
  class Test
  {
    #[ORM\Column(name: 'id', type: 'integer')]
    #[ORM\Id]
    #[ORM\GeneratedValue(strategy: 'AUTO')]
    private \$id;
  }
  " > Entity/Test.php

• Create the PHP script test.php to throw the error

  echo "<?php // reproduce.php
  require_once 'vendor/autoload.php';
  require_once 'Entity/Test.php';
  \$connection = \Doctrine\DBAL\DriverManager::getConnection(
    [
        'driver' => 'pdo_sqlite',
        'path' => tempnam(sys_get_temp_dir(), 'doctrine') . '.sqlite',
        'memory' => true,
    ],
    \$config = \Doctrine\ORM\ORMSetup::createAttributeMetadataConfiguration([__DIR__ . '/Entity'], true),
  );
  \$entityManager = new \Doctrine\ORM\EntityManager(\$connection, \$config);
  (new \Doctrine\ORM\Tools\SchemaTool(\$entityManager))->createSchema(\$entityManager->getMetadataFactory()->getAllMetadata());
  \$article = \$entityManager->find(App\Entity\Test::class, ['id' => [1234]]); // <-------- throws the warning we want
  " > reproduce.php

• Run the PHP script reproduce.php

  php reproduce.php
  

  You should get a PHP Warning: Array to string conversion

Expected behavior

It would be nice to get just an UnexpectedValueException explaining the problem.