get_device_id_by_address raises ValueError on empty device list

[PaulWinterstein]

When callingget_device_id_by_address (e.g. called by add_device) on an VideoIPath system without devices in inventory, the method raises a ValueError due to strict response validation. This prevents basic inventory API usage in fresh or test systems.

✅ Expected: Return None if no device is found, without raising an exception.
❌ Current: Raises ValueError("Response data is empty.")

Proposed solution: Handle empty device lists gracefully and return None as intended.