faces: Skip null entries when trying to resolve sensors
- sensors: Improve robustness of SensorDaemonInterface
We may end up calling methods of SensorDaemonInterface with empty strings or stringlists. Rather than relying on the daemon to do the right thing in that case, just do an early return since we know we will never get any useful data for an empty ID.
- faces: Skip null entries when trying to resolve sensors
If the list of requested sensors contains a null entry, we end up querying for all sensors, which leads to unexpected behaviour where removing the last sensor from a face suddenly adds all existing sensors. To avoid this, skip any requested entries that contain null.