Using RSF in react-native (messaging channel not subbed to setBackgroundMessageHandler)

[tad3j]

For the most part (auth and firestore modules) I was able to use this great package without any issues. Today I was implementing notifications and I've noticed that this library only subscribes to var unsubscribe = messaging.onMessage(emit); which results in notifications being emited only when app is open. https://github.com/n6g7/redux-saga-firebase/blob/master/src/messaging.js#L12

There is another event messaging.setBackgroundMessageHandler (which turns out it also works in JS version of firabase), which emits a message while app is not open (in background), which is usually more important on mobile devices.

Would there be a way to add this subscription?

I was looking through the code but I'm not sure if I could just add another subscriptions on line 12 and then somehow combine them (since message emitted is of same class in both cases), or would we need a completely new channel (according to code copy pasting function channel() should be easy to do, but is there a better way?). If anyone can show me how it should be done I'm also willing to get my hands dirty. :)

EDIT: After trying to copy channel() code I fugured that same approach won't work, since onMessage seems like expecting generator, but setBackgroundMessageHandler requires a callback that returns a promise. I guess that's why it doesn't fit into saga world?