While using the serviceWorkerRegistration.pushManager.subscribe
method from a ServiceWorker, the created endpoint
sometimes contains an "/undefined" at the end of the string.
For example, through a Chrome ServiceWorker : https://android.googleapis.com/gcm/send/xxx...xxx/undefined
I must say that I've got a valid Android Sender ID, and if remove this extra part, I'm able to send a push to the user.
Last but not least, this situation has happened with both Chrome and Firefox subscriptions.