Air Purifier discovered but not working
Hello,
I've added all my accessories in the Home App (see #22 ) but the Air Purifier is not working (it's added but becomes unresponsive).

Here are some details that might be helpful:

AIR PURIFIER:
Brand: Bimar
Model: VK-6070A
Type: PA98

LOGS:
(node:1091288) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'values' of undefined
    at AirPurifierAccessory.getSpeedFunction (/usr/local/lib/node_modules/homebridge-tuya-platform/lib/air_purifier_accessory.js:162:40)
    at new AirPurifierAccessory (/usr/local/lib/node_modules/homebridge-tuya-platform/lib/air_purifier_accessory.js:25:37)
    at TuyaPlatform.addAccessory (/usr/local/lib/node_modules/homebridge-tuya-platform/index.js:107:27)
    at TuyaPlatform.initTuyaSDK (/usr/local/lib/node_modules/homebridge-tuya-platform/index.js:86:12)
    at processTicksAndRejections (internal/process/task_queues.js:95:5)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:1091288) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:1091288) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

IMAGES:
![bimar](https://user-images.githubusercontent.com/78073930/120970777-266cec00-c76c-11eb-8976-53ccfc8c287d.jpeg)


Thanks for your hard work!