Hi!

I wanted to use your plugin, but I’ve got a jQuery error. In the functions.php file the loader_script() function has a bad line. Instead of d(window).load(function() {...}) I wrote d(window).on ("load", function() {...}) and it worked like a charm. You can also read the documentation of this function here: jQuery Load Event. It’s got deprecated.

Secondly, I wanted to use .svg file as preloader image. I downloaded WP SVG images plugin, so I can able to upload .svg files, but your plugin not wanted to accept it. But after a little modification in customizer.php, it worked. In the loader_sanitize_image_upload() function, I added a new type of MIME after png:

$formats = array(
                'jpg|jpeg|jpe' => 'image/jpeg',
                'gif'          => 'image/gif',
                'png'          => 'image/png',
		'svg'	       => 'image/svg+xml'
            );

After this, everything was fine for me! If you think this modifications are valid, apply them.