Facebook's 'PAGE plugin' https://developers.facebook.com/docs/plugins/page-plugin/ is provided to allow an events/calendar from fb to be displayed in a website.

However, there is a bug - the page/iframe is not displayed if the website visitor is (also) logged into fb. It works fine is the visitor is NOT a fb user (and is therefore not logged into fb). The bug is already reported to fb (back in 2021), but they are not responding to peoples' requests. see: https://developers.facebook.com/support/bugs/584988619248795/

The bug produces a console error msg:

ErrorUtils caught an error: Found null hrp, blocking mods: ExceptionDialog; non-blocking mods: ; response error: 1357032, summary: Something went wrong, description: Please try refreshing the Page or closing and reopening your browser window.

Is there a javascript way to detect this error, and thus display a suitable msg - rather than the revolving waiting symbols currently displayed.

I found this: getLoginStatusUrl here: Dertermine if user is logged in to Facebook w/o using Facebook api but don't understand how to use it.