Have UID from logged in user be a fallback for UID from URL

I'm creating a customer user menu and I have a view that pulls the UID from the URL using the "User:UID" contextual filter. This is working as expected.

What I want to do is if the UID is not in the URL that it would fall back to render the UID from the logged in user. I'm sure this is easily possible, but my skills with views is limited. Any help would be appreciated.