Get rid of deprecation warnings for trim() [PHP8.3] (yiisoft#20090)

Author: g41797

framework/web/UrlManager.php

@@ -413,7 +413,7 @@ public function createUrl($params)
         $anchor = isset($params['#']) ? '#' . $params['#'] : '';
         unset($params['#'], $params[$this->routeParam]);
 
-        $route = trim($params[0], '/');
+        $route = trim(isset($params[0]) ? $params[0] : '', '/');
         unset($params[0]);
 
         $baseUrl = $this->showScriptName || !$this->enablePrettyUrl ? $this->getScriptUrl() : $this->getBaseUrl();