Update error_pages.rst

Author: atailouloute

controller/error_pages.rst

@@ -193,17 +193,19 @@ To override non-HTML error output, the Serializer component needs to be installe
  $ composer require serializer
 
 The Serializer component has a built-in ``FlattenException`` normalizer
-(``ProblemNormalizer``) and JSON/XML/CSV/YAML encoders. When your application
+(:class:`Symfony\\Component\\Serializer\\Normalizer\\ProblemNormalizer`) and JSON/XML/CSV/YAML encoders. When your application
 throws an exception, Symfony can output it in one of those formats. If you want
 to change the output contents, create a new Normalizer that supports the
 ``FlattenException`` input::
 
  # src/App/Serializer/MyCustomProblemNormalizer.php
  namespace App\Serializer;
 
+ use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
+
  class MyCustomProblemNormalizer implements NormalizerInterface
  {
- public function normalize($exception, $format = null, array $context = [])
+ public function normalize($exception, string $format = null, array $context = [])
  {
  return [
  'content' => 'This is my custom problem normalizer.',
@@ -214,7 +216,7 @@ to change the output contents, create a new Normalizer that supports the
  ];
  }
 
- public function supportsNormalization($data, $format = null)
+ public function supportsNormalization($data, string $format = null)
  {
  return $data instanceof FlattenException;
  }
@@ -252,14 +254,14 @@ configuration option to point to it:
  https://symfony.com/schema/dic/services/services-1.0.xsd">
 
  <framework:config>
- <framework:error_controller>App\Controller\ErrorController::showAction</framework:error_controller>
+ <framework:error-controller>App\Controller\ErrorController::showAction</framework:error-controller>
  </framework:config>
 
  </container>
 
  .. code-block:: php
 
- // config/packages/twig.php
+ // config/packages/framework.php
  $container->loadFromExtension('framework', [
  'error_controller' => 'App\Controller\ErrorController::showAction',
  // ...