The unit of measurement % is not valid together with device class illuminance' when processing MQTT discovery message topic #16
Description
Newer HomeAssistant versions started complaining about the go-eControllers HomeAssistant integration via MQTT:
2025-10-24 17:20:55.870 ERROR (MainThread) [homeassistant.components.mqtt.entity] Error 'The unit of measurement `%` is not valid together with device class `illuminance`' when processing MQTT discovery message topic: 'homeassistant/sensor/go-e_<serial>/brightness_sensor/config', message: '{'state_topic': 'go-eController/<serial>/bri', 'device_class': 'illuminance', 'device': {'manufacturer': 'go-e', 'sw_version': '1.1.1', 'model': 'controller', 'identifiers': ['go-e_<serial>'], 'name': '<friendlyName>'}, 'unique_id': 'go-e_<serial>_brightness_sensor', 'unit_of_measurement': '%', 'value_template': '{{ ((value_json / 3300.0) ** 0.5 * 100) | round(1) }}', 'name': 'Brightness Sensor', 'icon': 'mdi:weather-sunny'}'