From eba33899062016221b33c3944bf47feda9a321ed Mon Sep 17 00:00:00 2001
From: Will Rossiter <will@fullscreen.io>
Date: Sat, 21 Jan 2023 08:36:44 +1300
Subject: [PATCH] fix: handle exceptions when using /0 as a URL

---
 code/Controllers/ModelAsController.php | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/code/Controllers/ModelAsController.php b/code/Controllers/ModelAsController.php
index 8f9233ca65..0165a3fbab 100644
--- a/code/Controllers/ModelAsController.php
+++ b/code/Controllers/ModelAsController.php
@@ -118,8 +118,9 @@ public function handleRequest(HTTPRequest $request)
     public function getNestedController()
     {
         $request = $this->getRequest();
+        $urlSegment = $request->param('URLSegment');
 
-        if (!$URLSegment = $request->param('URLSegment')) {
+        if ($urlSegment === null || $urlSegment === '') {
             throw new Exception('ModelAsController->getNestedController(): was not passed a URLSegment value.');
         }
 
@@ -130,13 +131,14 @@ public function getNestedController()
 
         // url encode unless it's multibyte (already pre-encoded in the database)
         $filter = URLSegmentFilter::create();
+
         if (!$filter->getAllowMultibyte()) {
-            $URLSegment = rawurlencode($URLSegment ?? '');
+            $urlSegment = rawurlencode($urlSegment ?? '');
         }
 
         // Select child page
         $tableName = DataObject::singleton(SiteTree::class)->baseTable();
-        $conditions = [sprintf('"%s"."URLSegment"', $tableName) => $URLSegment];
+        $conditions = [sprintf('"%s"."URLSegment"', $tableName) => $urlSegment];
         if (SiteTree::config()->get('nested_urls')) {
             $conditions[] = [sprintf('"%s"."ParentID"', $tableName) => 0];
         }