These aren't the errors you are searching for
... so you get an Error 404 message?
Did you know you can customize that as well?
The 9 Best 404 Error Pages We
has a cute roundup of them, as does
Funny 404 Pages fab 404 Error Page Gallery
34 brilliantly designed 404 error pages | Creative Bloq
60 Really Cool and Creative Error 404 Pages - Hongkiat
If your WP theme doesn't have a 404 page,
https://wordpress.org/plugins/404page/
will help you create one. You can direct people to your money pages, your optins.... lots of things!
'Tis a nifty thing to have.
Enjoy!