Panel crashes due to unknown NetworkManager device(?)

Here are the errors I get, the panel simply crashes shortly after starting up:

NetworkManager Found
DeviceAdded for unknown device type : /org/freedesktop/NetworkManager/Devices/3 : type : 30

(wf-panel:5936): GLib-CRITICAL **: 07:22:38.443: g_variant_get_type: assertion 'value != NULL' failed

(wf-panel:5936): GLib-CRITICAL **: 07:22:38.443: g_variant_type_equal: assertion 'g_variant_type_check (type1)' failed

(wf-panel:5936): GLib-CRITICAL **: 07:22:38.443: g_variant_get_string: assertion 'value != NULL' failed

(wf-panel:5936): GLib-CRITICAL **: 07:22:38.443: g_variant_get_type: assertion 'value != NULL' failed

(wf-panel:5936): GLib-CRITICAL **: 07:22:38.443: g_variant_type_is_subtype_of: assertion 'g_variant_type_check (type)' failed

(wf-panel:5936): GLib-CRITICAL **: 07:22:38.443: g_variant_get_boolean: assertion 'g_variant_is_of_type (value, G_VARIANT_TYPE_BOOLEAN)' failed
Gdk-Message: 07:22:40.532: Error reading events from display: Resource temporarily unavailable

Note this is a temporary system state, might not be easily reproducible (at least, I don't know how to do that)

Start by examining the panel's NetworkManager DeviceAdded handling, using the reported device type 30 and GLib critical messages as clues. Reproduce the temporary system state if possible, then verify that an unknown device does not crash the panel and that the reported warnings no longer occur.