commit 2e5e0565b50e2913468f3a3fbfcd9d77cadfb744
Author: Samuel Leathers <sam@appliedtrust.com>
Date:   Sat Aug 17 11:48:17 2013 -0500

    Adding exception

diff --git a/core/modules/book/lib/Drupal/book/BookExport.php b/core/modules/book/lib/Drupal/book/BookExport.php
index 8b367f7..62a5148 100644
--- a/core/modules/book/lib/Drupal/book/BookExport.php
+++ b/core/modules/book/lib/Drupal/book/BookExport.php
@@ -56,7 +56,7 @@ public function __construct(EntityManager $entityManager) {
    * @param \Drupal\node\NodeInterface $node
    *   The node to export.
    *
-   * @throws \Symfony\Component\HttpKernel\Exception\NotFoundHttpException
+   * @throws \Exception
    *   Thrown when the node was not attached to a book.
    *
    * @return array
@@ -65,7 +65,7 @@ public function __construct(EntityManager $entityManager) {
    */
   public function bookExportHtml(NodeInterface $node) {
     if (!isset($node->book)) {
-      throw new NotFoundHttpException();
+      throw new \Exception();
     }
 
     $tree = book_menu_subtree_data($node->book);