Ted here from Shopify. :-)
This is a known issue that has just occurred today and we apologise for the inconvenience caused. Our Devs are currently working on this, however, could you email firstname.lastname@example.org? When you do, you should receive an automated email back with a ticket number assigned. If you let me know what that ticket number is, I'll let the team know that you're store is also displaying this error. We should have this resolved as soon as possible.
Thanks a mill!