x-default language

I noticed that the x-default does not appear in Polylang’s source code. According to our experts, it is recommended to include it in order to redirect to the correct language if an issue occurs.

Here is the link to the Google documentation explaining this. (https://developers.google.com/search/blog/2023/05/x-default?hl=en)

Could you help me with this?