bug symfony#57297 [FrameworkBundle] not registered definitions must not be modified (xabbuh)

This PR was merged into the 5.4 branch.

Discussion
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[FrameworkBundle] not registered definitions must not be modified

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | Fix symfony#57294
| License       | MIT

Commits
-------

c9b117c not registered definitions must not be modified

Author: nicolas-grekas

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

@@ -1854,6 +1854,10 @@ private function registerSerializerConfiguration(array $config, ContainerBuilder
             $container->setParameter('serializer.default_context', $defaultContext);
         }
 
+        if (!$container->hasDefinition('serializer.normalizer.object')) {
+            return;
+        }
+
         $arguments = $container->getDefinition('serializer.normalizer.object')->getArguments();
         $context = [];