Merged requested to merge work/vpnerror into master
There are two cases where this error will be shown:
plasma-nm is built without support for that VPN because of missing optional dependencies.
NetworkManager is missing a runtime package for that VPN type, e.g. for openconnect one needs network-manager-openconnect on Ubuntu
The current error message is quite unhelpful since it doesn't tell what kind of thing is missing. Try to improve that a bit.
Not that this is the pinnacle of UX. I don't think there's a nice and easy way to guide the user to installing the right package.