storefront_html_tag_schema()
was deprecated in Storefront 2.0.2, but it looks like function was dropped completely on the wordpress.org-hosted version of the plugin. This causes a fatal error on child themes. I notice that the latest version of Storefront (2.0.3) has removed the function call from the html
tag altogether, so you can probably just remove it from html
in any child themes and it’ll be fine.
Curiously, the Github-hosted version of Storefront deprecates the function nicely, but the wordpress.org version simply removes the function definition. Some sort of discrepancy?