Thank you for bringing this to our attention. This warning can be safely ignored, as it does not impact the output assets of your application.

The compiled assets should function as expected. If you encounter any specific issues or need further assistance, please don't hesitate to reach out.

I have also noticed that there is a missing slash "/" in the output directory.

// JS pages (single page use)
(glob.sync(`${dir}/js/custom/**/*.js`) || []).forEach(file => {
    var output = `public/assets${file.replace(path.normalize(dir), '')}`;
    mix.scripts(file, output);
});

should be

var output = `public/assets/${file.replace(path.normalize(dir), '')}`;