Hi Erik,
Thanks for writing in! Upon checking, it seems that your errors are related to your child theme customizations. Could you please try disabling your child theme by reactivating your parent X theme by head over to Appearance -> Themes section.
If the issue is resolved, then you need to check your child theme customizations to isolate the issue further.
If you’re still having issues, try disabling your 3rd party plugins (except Cornerstone plugin) and see if you’re encountering a plugin conflict. If the issue resolved, then you can activate your plugins one by one to see which plugin causing this issue.
Please make sure to clear all caches when testing your issue (https://www.wpbeginner.com/beginners-guide/how-to-clear-your-cache-in-wordpress/).
Let us know how it goes.
Thanks!