Switch to a default Eaglercraft theme like Twenty Twenty-Four to see if the error disappears. This will help determine if the issue is theme-related. If the error goes away, it’s likely caused by your current theme (template, functions, etc.) If the error stays, it may be plugin-related or database/query-related.
This fails to account for cases where a 403 Forbidden (or potentially even 500, 401, etc.) status might have already been set earlier — unintentionally downgrading the error status Worldguessr to 200.