feat: theme error page

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

lib/private/legacy/OC_Template.php

@@ -21,6 +21,7 @@
  * @author Roeland Jago Douma <roeland@famdouma.nl>
  * @author Thomas Müller <thomas.mueller@tmit.eu>
  * @author Vincent Petry <vincent@nextcloud.com>
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
  *
  * @license AGPL-3.0
  *
@@ -38,7 +39,9 @@
  *
  */
 use OC\TemplateLayout;
+use OCP\AppFramework\Http\Events\BeforeTemplateRenderedEvent;
 use OCP\AppFramework\Http\TemplateResponse;
+use OCP\EventDispatcher\IEventDispatcher;
 use OCP\Util;
 
 require_once __DIR__.'/template/functions.php';
@@ -292,10 +295,17 @@ public static function printErrorPage($error_msg, $hint = '', $statusCode = 500)
 
 		http_response_code($statusCode);
 		try {
-			$content = new \OC_Template('', 'error', 'error', false);
-			$errors = [['error' => $error_msg, 'hint' => $hint]];
-			$content->assign('errors', $errors);
-			$content->printPage();
+			$response = new TemplateResponse(
+				'',
+				'error',
+				['errors' => [['error' => $error_msg, 'hint' => $hint]]],
+				TemplateResponse::RENDER_AS_ERROR,
+				$statusCode,
+			);
+			$event = new BeforeTemplateRenderedEvent(false, $response);
+			\OC::$server->get(IEventDispatcher::class)->dispatchTyped($event);
+
+			print($response->render());
 		} catch (\Exception $e) {
 			$logger = \OC::$server->getLogger();
 			$logger->error("$error_msg $hint", ['app' => 'core']);