Revert "dont’ fail hard if pages recurse with same path"

This reverts commit 9c5b8b6496.

# Conflicts:
#	system/src/Grav/Common/Page/Pages.php

CHANGELOG.md

@@ -3,9 +3,7 @@
 
 1. [](#improved)
    * Updated `bin/composer.phar` to latest `2.4.2` version [#3627](https://github.com/getgrav/grav/issues/3627)
-1. [](#bugfix)
-   * Don't fail hard if pages recurse with same page path
-   
+
 # v1.7.37.1
 ## 10/05/2022
 

system/src/Grav/Common/Page/Pages.php

@@ -1850,7 +1850,7 @@ class Pages
                 $this->children[$parent->path()][$page->path()] = ['slug' => $page->slug()];
             }
         } elseif ($parent !== null) {
-            return null;
+            throw new RuntimeException('Fatal error when creating page instances.');
         }
 
         // Build regular expression for all the allowed page extensions.