Gracefully handle empty XML configuration files

[pablo]

From linuxdev:

There is an unhandled exception in Configger.as, specifically in the function loadComplete(), and
specifically in the line:

var loadedXML:XML = XML((evt.target as URLLoader).data);

The exception is thrown when the XML exists, but it's empty. That scenario it's supposed to 
be checked in the following line with:

loadedXML.children().length() > 0

But the flow never reaches this point. This is 100% reproducible, at least in 5.7

[pablo]

Fixed in [2021]