Use case

1. Create a WebViewController
2. Register the callback for console messages with setOnConsoleMessage
3. If the same controller is reused later and we try to register the same callback with setOnConsoleMessage it's going to throw an Exception.

There is no real way to avoid this as there is no way to unregister that channel.

Proposal

To add a new method in the WebViewController class to unregister the one created by setOnConsoleMessage.

A workaround for this is to manually call:

webViewController.removeJavaScriptChannel(
  'fltConsoleMessage', // this is the channel name according to source code
);