diff --git a/core/lib/Drupal/Core/Template/TwigExtension.php b/core/lib/Drupal/Core/Template/TwigExtension.php
index 9d6dd1a..7069f1c 100644
--- a/core/lib/Drupal/Core/Template/TwigExtension.php
+++ b/core/lib/Drupal/Core/Template/TwigExtension.php
@@ -372,6 +372,9 @@ public function attachLibrary($library) {
    *
    * @return string|null
    *   The escaped, rendered output, or NULL if there is no valid output.
+   *
+   * @throws \Exception
+   *   When an object is passed that has no __toString method.
    */
   public function escapePlaceholder($env, $string) {
     return '<em class="placeholder">' . $this->escapeFilter($env, $string) . '</em>';
@@ -400,6 +403,9 @@ public function escapePlaceholder($env, $string) {
    * @return string|null
    *   The escaped, rendered output, or NULL if there is no valid output.
    *
+   * @throws \Exception
+   *   When an object is passed that has no __toString method.
+   *
    * @todo Refactor this to keep it in sync with theme_render_and_autoescape()
    *   in https://www.drupal.org/node/2575065
    */
@@ -483,6 +489,9 @@ public function escapeFilter(\Twig_Environment $env, $arg, $strategy = 'html', $
    * @return mixed
    *   The rendered output or an Twig_Markup object.
    *
+   * @throws \Exception
+   *   When an object is passed that has no __toString method.
+   *
    * @see render
    * @see TwigNodeVisitor
    */