This is the outcome for any input that doesn't produce a match. That pop-up uses an ancient (pre jQueryUI) jQuery Autocomplete plugin, recently updated to this fork which has a few updates for support of modern browsers and jQuery versions. But as far as I can tell, this isn't a new bug; it probably behaved in this way for as long as that site selector has been active.
One of the not-particularly-well-documented (or, one might argue, thought out) features of that plugin has to do with what happens if no results match. There's an option named
noRecord which defaults to the string
And so we get an undefined icon and an undefined description and, if selected, the value "No Records." for an instant until the pop-up is removed from the screen. Naturally, the site isn't changed as there's no site with the domain "No Records."
A fix for this, should anyone care enough to make one, would probably involve setting the
noRecord option to something a bit more descriptive than "No Records." and then testing against that new value when considering whether or not to render a match or accept a result.