throw on unknown action breaks react-devtools

[yesmeck]

Since react-devtools will also use postMessage to communicate with webview, so throw on unknown action breaks the react-devtools.

sketch-module-web-view/lib/inject-client-messaging.js

Lines 7 to 9 in e9dfe38

	' if (!actionName) {' +
	" throw new Error('missing action name')" +
	' }' +

[yesmeck]

@mathieudutour Why wontfix? I don't see actionName was used anywhere.

[mathieudutour]

It won't matter whether we throw or not because we completely replace the postMessage method. So the issue would be to design another mechanism to communicate with the webview - and we won't do that.