Possible to exclude archives that would be empty?

[Graham-Phillips]

My compress config creation function loops over many whitelabel folders, and creates zips of the assets it finds inside each white label:

var src = ['./asset/whitelabels/', '!.zip'];

grunt.file.expand({filter: 'isDirectory'}, module).forEach(function (dir) {

var compress = grunt.config.get('compress') || {};

	// set the config for this modulename-directory
	compress[dir] = {
		files:
				[
					{
						src: [
							dir + '**/graphics/**/*.png',
							dir + '**/core/**/*.mp3',

						]
					}
				],
		options:
				{
					archive: function () {
						return 'dist/' + dir.toLowerCase() + '.zip'
					}
				}
		};

	// save the new concat configuration
	grunt.config.set('compress', compress);
});

grunt.task.run('compress');

My problem is, if there were no assets within a particular whitelabel folder/subfolders, it creates an empty zip archive. I would like to skip the creation of empty archives, is it possible to specify that?
thanks