[FIX] Friendly url in php 8.2.

Author: Seiger

core/src/UrlProcessor.php

@@ -543,8 +543,8 @@ public function getHiddenIdFromAlias(int $parentid, string $alias): ?int
     public function makeUrl(int $id, string $alias = '', string $args = '', string $scheme = ''): string
     {
         $virtualDir = $this->core->getConfig('virtual_dir');
-        $f_url_prefix = $this->core->getConfig('friendly_url_prefix');
-        $f_url_suffix = $this->core->getConfig('friendly_url_suffix');
+        $f_url_prefix = $this->core->getConfig('friendly_url_prefix', '');
+        $f_url_suffix = $this->core->getConfig('friendly_url_suffix', '');
 
         if ($args !== '') {
             // add ? or & to $args if missing