Return GraphQL JSON response in case of JSON Input error instead of Internal Server Error

Controller/GraphQLiteController.php

@@ -27,6 +27,7 @@
 use Symfony\Component\Routing\Route;
 use Symfony\Component\Routing\RouteCollection;
 use TheCodingMachine\GraphQLite\Bundle\Context\SymfonyGraphQLContext;
+use TheCodingMachine\GraphQLite\Bundle\Exceptions\JsonException;
 
 /**
  * Listens to every single request and forward Graphql requests to Graphql Webonix standardServer.
@@ -80,12 +81,25 @@ public function handleRequest(Request $request): Response
 
         if (strtoupper($request->getMethod()) === "POST" && empty($psr7Request->getParsedBody())) {
             $content = $psr7Request->getBody()->getContents();
-            $parsedBody = json_decode($content, true);
-            if (json_last_error() !== JSON_ERROR_NONE) {
-                throw new \RuntimeException('Invalid JSON received in POST body: '.json_last_error_msg());
+            try {
+                $parsedBody = json_decode(
+                    json: $content,
+                    associative: true,
+                    flags: \JSON_THROW_ON_ERROR
+                );
+            } catch (\JsonException $e) {
+                throw JsonException::create(
+                    reason: $e->getMessage(),
+                    code: Response::HTTP_UNSUPPORTED_MEDIA_TYPE,
+                    previous:$e
+                );
             }
-            if (!is_array($parsedBody)){
-                throw new \RuntimeException('Expecting associative array from request, got ' . gettype($parsedBody));
+
+            if (!is_array($parsedBody)) {
+                throw JsonException::create(
+                    reason: 'Expecting associative array from request, got ' . gettype($parsedBody),
+                    code: Response::HTTP_UNPROCESSABLE_ENTITY
+                );
             }
             $psr7Request = $psr7Request->withParsedBody($parsedBody);
         }

DependencyInjection/Configuration.php

@@ -11,7 +11,7 @@ class Configuration implements ConfigurationInterface
     /**
      * @return TreeBuilder
      */
-    public function getConfigTreeBuilder()
+    public function getConfigTreeBuilder(): TreeBuilder
     {
         $treeBuilder = new TreeBuilder('graphqlite');
         $rootNode = $treeBuilder->getRootNode();

EventListener/ExceptionListener.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace TheCodingMachine\GraphQLite\Bundle\EventListener;
+
+use GraphQL\Error\Error;
+use GraphQL\Executor\ExecutionResult;
+use Symfony\Component\HttpFoundation\JsonResponse;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use TheCodingMachine\GraphQLite\Exceptions\GraphQLExceptionInterface;
+use TheCodingMachine\GraphQLite\Http\HttpCodeDecider;
+use TheCodingMachine\GraphQLite\Http\HttpCodeDeciderInterface;
+
+class ExceptionListener
+{
+    private readonly HttpCodeDeciderInterface $httpCodeDecider;
+
+    public function __construct(
+        ?HttpCodeDeciderInterface $httpCodeDecider = null,
+    ) {
+        $this->httpCodeDecider = $httpCodeDecider ?? new HttpCodeDecider();
+    }
+
+    public function onKernelException(ExceptionEvent $event): void
+    {
+        $exception = $event->getThrowable();
+
+        if ($exception instanceof GraphQLExceptionInterface) {
+            $result = new ExecutionResult(
+                errors: [new Error(
+                    message: $exception->getMessage(),
+                    previous: $exception,
+                    extensions: $exception->getExtensions()
+                )]
+            );
+
+            $response = new JsonResponse($result->toArray(), $this->httpCodeDecider->decideHttpStatusCode($result));
+
+            $event->setResponse($response);
+        }
+    }
+}

Exceptions/JsonException.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace TheCodingMachine\GraphQLite\Bundle\Exceptions;
+
+use Exception;
+use TheCodingMachine\GraphQLite\Exceptions\GraphQLException;
+
+class JsonException extends GraphQLException
+{
+    public static function create(?string $reason = null, int $code = 400, Exception $previous = null): self
+    {
+        return new self(
+            message: 'Invalid JSON.',
+            code: $code,
+            previous: $previous,
+            extensions: ['reason' => $reason]
+        );
+    }
+}

Resources/config/container/graphqlite.xml

@@ -90,6 +90,10 @@
             <tag name="routing.route_loader"/>
         </service>
 
+        <service id="TheCodingMachine\GraphQLite\Bundle\EventListener\ExceptionListener">
+            <tag name="kernel.event_listener" event="kernel.exception" method="onKernelException" />
+        </service>
+
         <service id="TheCodingMachine\GraphQLite\Bundle\Mappers\RequestParameterMiddleware">
             <tag name="graphql.parameter_middleware"/>
         </service>

Tests/FunctionalTest.php

@@ -104,6 +104,28 @@ public function testErrors(): void
         $kernel = new GraphQLiteTestingKernel();
         $kernel->boot();
 
+        $request = Request::create('/graphql', 'POST', [], [], [], ['CONTENT_TYPE' => 'application/json'], '{"query":"{ invalidJsonSyntax }"');
+
+        $response = $kernel->handle($request);
+
+        $this->assertSame(415, $response->getStatusCode());
+
+        $result = json_decode($response->getContent(), true);
+
+        $this->assertSame('Invalid JSON.', $result['errors'][0]['message']);
+        $this->assertSame('Syntax error', $result['errors'][0]['extensions']['reason']);
+
+        $request = Request::create('/graphql', 'POST', [], [], [], ['CONTENT_TYPE' => 'application/json'], '"Unexpected Json Content"');
+
+        $response = $kernel->handle($request);
+
+        $this->assertSame(422, $response->getStatusCode());
+
+        $result = json_decode($response->getContent(), true);
+
+        $this->assertSame('Invalid JSON.', $result['errors'][0]['message']);
+        $this->assertSame('Expecting associative array from request, got string', $result['errors'][0]['extensions']['reason']);
+
         $request = Request::create('/graphql', 'GET', ['query' => '
         { 
           notExists