Thank you, please clarify how I can replicate that fatal error on your end. Also, confirm the permission for plugins deactivation and switching to the parent theme.
At the moment, we do not see such an error on your end. Please clarify how often this error happens. If it happens often, please disable all 3rd party plugins and recheck whether it shows or not.
The error logs show that the theme was not updated correctly. So I suggest you reinstall the theme via Dashboard -> Themes -> Add new. Then clear the site/server/browser cache and recheck the issue.