Comment 6 for bug 1899262

wpa_supplicant exponse properties of the interface that you can read using dbus command such as. Now if the property is empy you should just expose as empty and not fail as it is in the code.

sudo dbus-send --system --print-reply --dest=fi.w1.wpa_supplicant1 /fi/w1/wpa_supplicant1/Interfaces/1 org.freedesktop.DBus.Properties.GetAll string:fi.w1.wpa_supplicant1.Interface

This kind of interface is used by other network services aka connman. I have tested on ubuntu-core and ubuntu 18.04