The error is due to the site trying to import a font named ‘Default’ which of course does not exist and hence the error. Was there any change made to the source files or in the theme options to import a Default font? If not, pls share a link to the site and a temp access to WP admin and we will take a look at this issue. Thanks.
I chose a font other than ‘Theme Default’ in Site Logo -> ‘Text Logo Font’ and the error went away. Actually a Theme Default for a logo does not make sense since most users would use an image or a customized font for a text logo. Will try to get this fixed in the next update. Thanks for bringing this to our attention.