unsubscribe() method interaction with event loop

[annevk]

Reading https://w3c.github.io/push-api/#dom-pushsubscription-unsubscribe it's rather unclear to me what is supposed to happen on the main thread and what happens in parallel. In fact, it almost seems like this could have been a synchronous method from the perspective of the caller?

[saschanaz]

I think it's reasonable to make it async to make sure the unsubscribe request is passed to the backend server. But then it doesn't say anything about the failure case, e.g. throw error or return false?