Comment 48 for bug 558841

after much digging I've managed to determine that this is probably some kind of race condition between the bluetooth_client_get_model not returning a fully populated model with all the devices in it and the subsequent call to device_changed and how the NULL default_iter in there is used in update_discoverability

This looks like a hard one to fix, there might be the need to wait for the bluetooth client model to be updated before we run device_changed... Or at least respond to the signals in a more robust way, the signals are emitted on the bluetooth client model so it may be possible to work around this.