Error on init SDK in flutter

Error on init SDK in flutter

Hi, I have a problem when init SalesIQ SDK in flutter. I have used the correct appKey and accessKey but still error on init.
Here is the guide that I have used: https://www.zoho.com/salesiq/help/developer-guides/flutter-sdk-event-handler-chatEventChannel.html. I also attached the error message on my console.
Please advise me thanks...