Just adlib. Just 1 stitch. Wont be noticed.

I would just wing it. (Pun kind of intended) and just use whatever’s next to it.

Surt and jaj
Are right. It is just one stitch and only you know. When I first started something like that would give me a panic attack🐱 so afraid someone would point at it and go "wrong". Now it makes it unique. Peace. Pam

Just look at what's around it and pick a similar color. Are you sure is shouldn't just be left blank? If you really feel there should be a stitch there, like I said, just pick a color. As long as it's not glaringly different, trust me, no-one will notice. I've "fixed" many a pattern when I've put a stitch wrong. Probably not even the designer will be able to tell!