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

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]
+        );
+    }
+}

src/Controller/GraphQLiteController.php

@@ -1,29 +1,30 @@
 <?php
 
-
 namespace TheCodingMachine\GraphQLite\Bundle\Controller;
 
-
-use GraphQL\Executor\ExecutionResult;
-use GraphQL\Server\ServerConfig;
-use GraphQL\Server\StandardServer;
-use GraphQL\Upload\UploadMiddleware;
+use GraphQL\Error\Error;
 use Laminas\Diactoros\ResponseFactory;
 use Laminas\Diactoros\ServerRequestFactory;
 use Laminas\Diactoros\StreamFactory;
 use Laminas\Diactoros\UploadedFileFactory;
+use Symfony\Bridge\PsrHttpMessage\Factory\PsrHttpFactory;
+use TheCodingMachine\GraphQLite\Http\HttpCodeDecider;
+use TheCodingMachine\GraphQLite\Http\HttpCodeDeciderInterface;
+use GraphQL\Executor\ExecutionResult;
+use GraphQL\Server\ServerConfig;
+use GraphQL\Server\StandardServer;
+use GraphQL\Upload\UploadMiddleware;
 use Psr\Http\Message\ServerRequestInterface;
 use RuntimeException;
-use Symfony\Bridge\PsrHttpMessage\Factory\PsrHttpFactory;
 use Symfony\Bridge\PsrHttpMessage\HttpMessageFactoryInterface;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\Routing\Route;
 use Symfony\Component\Routing\RouteCollection;
 use TheCodingMachine\GraphQLite\Bundle\Context\SymfonyGraphQLContext;
-use TheCodingMachine\GraphQLite\Http\HttpCodeDecider;
-use TheCodingMachine\GraphQLite\Http\HttpCodeDeciderInterface;
+use TheCodingMachine\GraphQLite\Bundle\Exceptions\JsonException;
+
 use function array_map;
 use function class_exists;
 use function json_decode;
@@ -80,13 +81,20 @@ 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) {
+                return $this->invalidJsonBodyResponse($e);
             }
-            if (!is_array($parsedBody)){
-                throw new \RuntimeException('Expecting associative array from request, got ' . gettype($parsedBody));
+
+            if (!is_array($parsedBody)) {
+                return $this->invalidRequestBodyExpectedAssociativeResponse($parsedBody);
             }
+
             $psr7Request = $psr7Request->withParsedBody($parsedBody);
         }
 
@@ -125,4 +133,51 @@ private function handlePsr7Request(ServerRequestInterface $request, Request $sym
 
         throw new RuntimeException('Only SyncPromiseAdapter is supported');
     }
+
+    private function invalidJsonBodyResponse(\JsonException $e): JsonResponse
+    {
+        $jsonException = JsonException::create(
+            reason: $e->getMessage(),
+            code: Response::HTTP_UNSUPPORTED_MEDIA_TYPE,
+            previous: $e,
+        );
+        $result = new ExecutionResult(
+            null,
+            [
+                new Error(
+                    'Invalid JSON.',
+                    previous: $jsonException,
+                    extensions: $jsonException->getExtensions(),
+                ),
+            ]
+        );
+
+        return new JsonResponse(
+            $result->toArray($this->debug),
+            $this->httpCodeDecider->decideHttpStatusCode($result)
+        );
+    }
+
+    private function invalidRequestBodyExpectedAssociativeResponse(mixed $parsedBody): JsonResponse
+    {
+        $jsonException = JsonException::create(
+            reason: 'Expecting associative array from request, got ' . gettype($parsedBody),
+            code: Response::HTTP_UNPROCESSABLE_ENTITY,
+        );
+        $result = new ExecutionResult(
+            null,
+            [
+                new Error(
+                    'Invalid JSON.',
+                    previous: $jsonException,
+                    extensions: $jsonException->getExtensions(),
+                ),
+            ]
+        );
+
+        return new JsonResponse(
+            $result->toArray($this->debug),
+            $this->httpCodeDecider->decideHttpStatusCode($result)
+        );
+    }
 }

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