not registered definitions must not be modified

Author: xabbuh

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 = [];