Add default (empty) arguments to renderers.

src/Renderer/PhpRenderer.php

@@ -16,7 +16,7 @@ class PhpRenderer implements Renderer
 	/**
 	 * @inheritDoc
 	 */
-	public function render(object $arguments): string
+	public function render(object $arguments = new \stdClass()): string
 	{
 		// Extract render arguments.
 		extract((array) $arguments);

src/Renderer/Renderer.php

@@ -12,5 +12,5 @@ interface Renderer
 	 * @param object $arguments View arguments.
 	 * @return string Produced view.
 	 */
-	function render(object $arguments): string;
+	function render(object $arguments = new \stdClass()): string;
 }

src/Router/Controller.php

@@ -98,7 +98,7 @@ abstract class Controller
 	 * @param string|null $contentType The content type of the response.
 	 * @return ResponseInterface Built response.
 	 */
-	public function render(Renderer $renderer, object $arguments, StatusCode $statusCode = StatusCode::OK, ?string $contentType = null): ResponseInterface
+	public function render(Renderer $renderer, object $arguments = new \stdClass(), StatusCode $statusCode = StatusCode::OK, ?string $contentType = null): ResponseInterface
 	{
 		return $this->newResponse($statusCode, $contentType ?? null, $renderer->render($arguments));
 	}