[HttpKernel] Fix FileLinkFormatter with empty xdebug.file_link_format

Author: fancyweb

Debug/FileLinkFormatter.php

@@ -44,7 +44,7 @@ class FileLinkFormatter
      */
     public function __construct(string $fileLinkFormat = null, RequestStack $requestStack = null, string $baseDir = null, string|\Closure $urlFormat = null)
     {
-        $fileLinkFormat = (self::FORMATS[$fileLinkFormat] ?? $fileLinkFormat) ?: ini_get('xdebug.file_link_format') ?: get_cfg_var('xdebug.file_link_format');
+        $fileLinkFormat = (self::FORMATS[$fileLinkFormat] ?? $fileLinkFormat) ?: ini_get('xdebug.file_link_format') ?: get_cfg_var('xdebug.file_link_format') ?: false;
         if ($fileLinkFormat && !\is_array($fileLinkFormat)) {
             $i = strpos($f = $fileLinkFormat, '&', max(strrpos($f, '%f'), strrpos($f, '%l'))) ?: \strlen($f);
             $fileLinkFormat = [substr($f, 0, $i)] + preg_split('/&([^>]++)>/', substr($f, $i), -1, \PREG_SPLIT_DELIM_CAPTURE);