Invalid HCHO value format for device K1Z-UK-xxxxxx: NONE

[nsleigh]

Describe the bug
I am seeing a warning in the logs and the HCHO value is Unknown in the UI. This is being reported by the a fan model 438E (DYSON PURIFIER COOL).

Not a big issue but thought I'd report it.

Debug Log
I think this is relavent part of the log:

2025-12-23 15:35:06.328 INFO (paho-mqtt-client-5613de93-a4b8-41be-93dc-6198bfe8d16c) [custom_components.hass_dyson.device] MQTT MESSAGE RECEIVED for K1Z-UK-xxxxxx - Topic: 438E/K1Z-UK-xxxxxx/status/current 2025-12-23 15:35:06.328 INFO (paho-mqtt-client-5613de93-a4b8-41be-93dc-6198bfe8d16c) [custom_components.hass_dyson.device] MQTT PARSED DATA for K1Z-UK-xxxxxx: {'msg': 'ENVIRONMENTAL-CURRENT-SENSOR-DATA', 'time': '2025-12-23T15:35:06.000Z', 'data': {'tact': '2943', 'hact': '0055', 'pm25': '0004', 'pm10': '0002', 'va10': '0005', 'noxl': '0003', 'p25r': '0005', 'p10r': '0005', 'hcho': 'NONE', 'hchr': 'NONE', 'sltm': 'OFF'}}

[cmgrayb]

Thank you for the report. We have added a filter for devices which provide a sensor key for formaldehyde but 'NONE' for a value in v0.22.0, expected to release December 24th. v0.22.0-beta.2 has been released if you would like to test it earlier.