Preventing broken links in the sidebar

I recently added a link to my sidebar and was confused because it did not work. So I checked the link and everything looked good.
image image
I was also able to open the link in a new tab.

But then I identified the problem:
I forgot to add the slash at the beginning. I know I made this mistake before, but then I was not able to save until I corrected the link.
This is a screenshot taken on an instance which last update happened in the middle of March. So probably that check was lost in FIX: Simplify sidebar custom link implementation (#26201) · discourse/discourse@e3cfb19 · GitHub

Is it possible to re-add this warning when you create a link like I did?