fix(jsonapi): handle missing attributes in ErrorNormalizer

Fixes undefined array key warning when normalizing exceptions
that don't have attributes in their normalized structure.

This typically occurs with ItemNotFoundException when invalid
resource identifiers are provided.

Author: daFish

features/jsonapi/errors.feature

@@ -61,3 +61,13 @@ Feature: JSON API error handling
     And the JSON node "errors[0].status" should be equal to 404
     And the JSON node "errors[0].detail" should exist
     And the JSON node "errors[0].type" should exist
+
+  Scenario: Get a proper error when ItemNotFoundException is thrown from a provider
+    When I send a "GET" request to "/jsonapi_error_test/nonexistent"
+    Then the response status code should be 404
+    And the response should be in JSON
+    And the header "Content-Type" should be equal to "application/vnd.api+json; charset=utf-8"
+    And the JSON node "errors" should exist
+    And the JSON node "errors[0].status" should exist
+    And the JSON node "errors[0].title" should exist
+    And the JSON node "errors[0].id" should exist

src/JsonApi/Serializer/ErrorNormalizer.php

@@ -35,6 +35,15 @@ public function __construct(private ?NormalizerInterface $itemNormalizer = null)
     public function normalize(mixed $object, ?string $format = null, array $context = []): array
     {
         $jsonApiObject = $this->itemNormalizer->normalize($object, $format, $context);
+
+        if (!isset($jsonApiObject['data']['attributes'])) {
+            return ['errors' => [[
+                'id' => $jsonApiObject['data']['id'] ?? uniqid('error_', true),
+                'status' => (string) (method_exists($object, 'getStatusCode') ? $object->getStatusCode() : 500),
+                'title' => method_exists($object, 'getMessage') ? $object->getMessage() : 'An error occurred',
+            ]]];
+        }
+
         $error = $jsonApiObject['data']['attributes'];
         $error['id'] = $jsonApiObject['data']['id'];
         if (isset($error['type'])) {

tests/Fixtures/TestBundle/ApiResource/JsonApiErrorTestResource.php

@@ -0,0 +1,36 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\ApiResource;
+
+use ApiPlatform\Metadata\ApiProperty;
+use ApiPlatform\Metadata\ApiResource;
+use ApiPlatform\Metadata\Get;
+use ApiPlatform\Tests\Fixtures\TestBundle\State\JsonApiErrorTestProvider;
+
+#[ApiResource(
+    operations: [
+        new Get(
+            uriTemplate: '/jsonapi_error_test/{id}',
+            provider: JsonApiErrorTestProvider::class,
+        ),
+    ],
+    formats: ['jsonapi' => ['application/vnd.api+json']],
+)]
+class JsonApiErrorTestResource
+{
+    #[ApiProperty(identifier: true)]
+    public string $id;
+
+    public string $name;
+}

tests/Fixtures/TestBundle/State/JsonApiErrorTestProvider.php

@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\State;
+
+use ApiPlatform\Metadata\Exception\ItemNotFoundException;
+use ApiPlatform\Metadata\Operation;
+use ApiPlatform\State\ProviderInterface;
+use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\JsonApiErrorTestResource;
+
+class JsonApiErrorTestProvider implements ProviderInterface
+{
+    public function provide(Operation $operation, array $uriVariables = [], array $context = []): object|array|null
+    {
+        $id = $uriVariables['id'] ?? null;
+
+        if ('existing' === $id) {
+            $resource = new JsonApiErrorTestResource();
+            $resource->id = $id;
+            $resource->name = 'Existing Resource';
+
+            return $resource;
+        }
+
+        throw new ItemNotFoundException(\sprintf('Resource "%s" not found.', $id));
+    }
+}