diff --git a/core/lib/Drupal/Core/Theme/Registry.php b/core/lib/Drupal/Core/Theme/Registry.php
index 094780a10e..a562b20dba 100644
--- a/core/lib/Drupal/Core/Theme/Registry.php
+++ b/core/lib/Drupal/Core/Theme/Registry.php
@@ -485,6 +487,7 @@ protected function processExtension(array &$cache, $name, $type, $theme, $path)
         // system.module to declare theme functions on behalf of core .include
         // files.
         if (isset($info['file'])) {
+          throw new \Exception();
           $include_file = isset($info['path']) ? $info['path'] : $path;
           $include_file .= '/' . $info['file'];
           include_once $this->root . '/' . $include_file;