I see a flash of white text on a dark background, then "Application error: a client-side exception has occurred (see the browser console for more information)." in black on the same very dark background.
Chrome on Win 10
this is probably happening if you're viewing a note that has been deleted. since i had 10000+ notes created on the day it launched i set up a pg_cron batch to delete empty notes that are >30 min old.
if not, can you share the url you're seeing it on? thanks for letting me know!