Error handling: Rename renderers to formatters

Refs #1641.

src/Foundation/ErrorHandling/WhoopsFormatter.php

@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Foundation\ErrorHandling;
+
+use Franzl\Middleware\Whoops\WhoopsRunner;
+use Psr\Http\Message\ResponseInterface as Response;
+use Psr\Http\Message\ServerRequestInterface as Request;
+
+class WhoopsFormatter implements HttpFormatter
+{
+    public function format(HandledError $error, Request $request): Response
+    {
+        return WhoopsRunner::handle($error->getError(), $request)
+            ->withStatus($error->getStatusCode());
+    }
+}