Only add filetime when file is given

[Ivo Bathke]

In vendor/therealworld/tools-plugin/Traits/ViewConfigTrait.php:136 it should check if a file is given.
Otherwise this will break other modules f.e. CSS loading in https://github.com/OXID-eSales/ddoe-wysiwyg-editor-module

http://localhost:8010/modules/ddoe/wysiwyg/?1613030966out/src/css/overlay.min.css

So this should check if $file is not empty:
if (!isset($aParts[1]) && $sFile) {