Unexpected terminations via D-Bus

[Marcel Holtmann]

Hi guys,

so I started playing with the new D-Bus interface and it seems it has
still some issues in handling unexpected usage. So for example by
accident, I triggered a scan with an empty parameter dictionary and this
happens:

RTM_NEWLINK, IFLA_IFNAME: Interface 'wlan0' added
wpas_dbus_handler_scan[dbus]: Scan type not specified

After that the daemon terminates. This is a pretty bad behavior. Either
we should return a proper error and continue or just fallback to some
default parameters.

I haven't checked any other method calls so far, but there might be
others.

Regards

Marcel