Hello guys,

When user input a none-existing url like:
https://classifieds.demoflynax.com/sdfs

It shows the undefined page, where I can edit content, which is fine.

But if users visit a none-existing listing url, whether the listing is removed, inactive, or expired, which is more common, for example:
https://classifieds.demoflynax.com/p...st-48-642.html
I added number "2" at the end of the url to replicate the none-existing listing

The original url is without "2" at the end:
https://classifieds.demoflynax.com/p...-st-48-64.html

As you can see, it shows all sort of stuffs like: book now, average price, price history, nearby school, etc. Which not looking nice.
So how do I redirect these none-existing listing url to the undefined page? Or better yet, another page I can edit content for none-existing listing, say I create a new page with page key "404_listing"

Thank you for such a great script.