Access request actor in error handler

src/Admin/AdminServiceProvider.php

@@ -49,6 +49,7 @@ public function register()
 
         $this->container->singleton('flarum.admin.middleware', function () {
             return [
+                HttpMiddleware\InjectActorReference::class,
                 'flarum.admin.error_handler',
                 HttpMiddleware\ParseJsonBody::class,
                 HttpMiddleware\StartSession::class,

src/Api/ApiServiceProvider.php

@@ -57,6 +57,7 @@ public function register()
 
         $this->container->singleton('flarum.api.middleware', function () {
             return [
+                HttpMiddleware\InjectActorReference::class,
                 'flarum.api.error_handler',
                 HttpMiddleware\ParseJsonBody::class,
                 Middleware\FakeHttpMethods::class,

src/Forum/ForumServiceProvider.php

@@ -58,6 +58,7 @@ public function register()
 
         $this->container->singleton('flarum.forum.middleware', function () {
             return [
+                HttpMiddleware\InjectActorReference::class,
                 'flarum.forum.error_handler',
                 HttpMiddleware\ParseJsonBody::class,
                 HttpMiddleware\CollectGarbage::class,

src/Http/ActorReference.php

@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Http;
+
+use Flarum\User\User;
+
+class ActorReference
+{
+    /**
+     * @var User
+     */
+    private $actor;
+
+    public function setActor(User $actor)
+    {
+        $this->actor = $actor;
+    }
+
+    public function getActor(): User
+    {
+        return $this->actor;
+    }
+}

src/Http/Middleware/InjectActorReference.php

@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Http\Middleware;
+
+use Flarum\Http\RequestUtil;
+use Flarum\User\Guest;
+use Psr\Http\Message\ResponseInterface as Response;
+use Psr\Http\Message\ServerRequestInterface as Request;
+use Psr\Http\Server\MiddlewareInterface as Middleware;
+use Psr\Http\Server\RequestHandlerInterface as Handler;
+
+class InjectActorReference implements Middleware
+{
+    public function process(Request $request, Handler $handler): Response
+    {
+        $request = RequestUtil::withActor($request, new Guest);
+
+        return $handler->handle($request);
+    }
+}

src/Http/RequestUtil.php

@@ -16,11 +16,23 @@ class RequestUtil
 {
     public static function getActor(Request $request): User
     {
-        return $request->getAttribute('actor');
+        return $request->getAttribute('actorReference')->getActor();
     }
 
     public static function withActor(Request $request, User $actor): Request
     {
-        return $request->withAttribute('actor', $actor);
+        $actorReference = $request->getAttribute('actorReference');
+
+        if (! $actorReference) {
+            $actorReference = new ActorReference;
+            $request = $request->withAttribute('actorReference', $actorReference);
+        }
+
+        $actorReference->setActor($actor);
+
+        // @deprecated in 1.0
+        $request = $request->withAttribute('actor', $actor);
+
+        return $request;
     }
 }