fix(qubes-setup-dnat-to-ns): handle null dns debus response as error

python typings indicate that resolve1.Get may return None.

Handle this possibility as failure, falling back to resolv.conf

Author: 3np

network/qubes-setup-dnat-to-ns

@@ -48,6 +48,7 @@ def get_dns_resolv_conf():
     return nameservers
 
 def get_dns_resolved():
+    dns = []
     try:
         bus = dbus.SystemBus()
     except dbus.exceptions.DBusException as s:
@@ -60,6 +61,9 @@ def get_dns_resolved():
         dns = resolve1.Get('org.freedesktop.resolve1.Manager',
                            'DNS',
                            dbus_interface='org.freedesktop.DBus.Properties')
+        if dns is Nothing:
+            return get_dns_resolv_conf()
+
     except dbus.exceptions.DBusException as s:
         error = s.get_dbus_name()
         if error in (