"Cannot read property 'dnsmasq' of null"

Having just installed OpenWRT for the first time, an error message greets me on the top of the Status -> Overview page:

Cannot read property 'dnsmasq' of null

I searched the forum but didn't find any matches; what might I do to get rid of it? It goes away after I click "Dismiss", but comes back after a reboot.

Reflash the latest stable OpenWrt release.
Perform factory reset if the issue persists.