Throw not found exception if dataset doesn't exist.

modules/dkan_js_frontend/src/Controller/Page.php

@@ -3,16 +3,64 @@
 namespace Drupal\dkan_js_frontend\Controller;
 
 use Drupal\Core\Controller\ControllerBase;
+use Drupal\Core\Path\CurrentPathStack;
+use Drupal\metastore\Exception\MissingObjectException;
+use Drupal\metastore\MetastoreService;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 /**
  * The Page controller.
  */
 class Page extends ControllerBase {
 
+  /**
+   * Metastore service.
+   */
+  private MetastoreService $service;
+
+  /**
+   * The current path.
+   *
+   * @var \Drupal\Core\Path\CurrentPathStack
+   */
+  protected $currentPath;
+
+  /**
+   * Inherited.
+   *
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('dkan.metastore.service'),
+      $container->get('path.current')
+    );
+  }
+
+  /**
+   * Constructor.
+   */
+  public function __construct(MetastoreService $service, CurrentPathStack $current_path) {
+    $this->service = $service;
+    $this->currentPath = $current_path;
+  }
+
   /**
    * Returns a render-able array.
    */
   public function content() {
+    $path_parts = explode('/', $this->currentPath->getPath());
+
+    if (is_array($path_parts) && count($path_parts) === 3 && $path_parts[1] === 'dataset') {
+      try {
+        $this->service->get('dataset', $path_parts[2]);
+      }
+      catch (MissingObjectException $exception) {
+        throw new NotFoundHttpException();
+      }
+    }
+
     return [
       '#theme' => 'page__dkan_js_frontend',
     ];