Sorry Tom,
This was an issue not with your theme update but a plugin, Async JavaScript. I saw you recommended this plugin but I need to do more research before I move forward with it. It was not due to updating the theme.
I also switched to SVG for the icons, but then I was getting the same error as above but for the arial font family.
If you do have recommended setting for the Async JavaScript plugin I’d be very interested.
Thank you for all you do!