Hummingbird empty JS caching files

Hey there,

i just installed Hummingbird and it works great so far with one exception: I've moved all the JS files to the bottom of the page in minification and the site still works well. Unfortunately Hummingbird still includes an empty JS caching files in the header which isn't a big problem but of course one request to the server that isn't needed and also one that is annoying google pagespeed insights

Any chance to get this empty thing removed?

Here's what it looks like:

<script type='text/javascript' src='https://handy-stativ.com/wp-content/uploads/wp-hummingbird-cache/77b4521f3ad0407e0d6a4ab428d97873.js.pagespeed.jm.1B2M2Y8Asg.js'></script>

Thanks,
Frank