It's blank for search engines. The page outputs a 404 which would appropriate for a file which has been removed.
You can change it if you want, the full source code is there:
In \core\page\file_download.php find:
Code:
// could not load the file
if (!$file)
{
coreFunctions::output404();
//coreFunctions::redirect(coreFunctions::getCoreSitePath() . "/index." . SITE_CONFIG_PAGE_EXTENSION);
}
Replace with:
Code:
// could not load the file
if (!$file)
{
coreFunctions::redirect(coreFunctions::getCoreSitePath() . "/index." . SITE_CONFIG_PAGE_EXTENSION);
}
Or wherever you want it to redirect to.