Did you setup OneSignal to send Web Push Notifications? The discourse-onesignal plugin should only be used for iOS notifications, the screen above with the “Service Worker 404” error does not look like an iOS issue.
So, if you’re trying to set up OneSignal for an iOS app, the first step is good (installing the discourse-onesignal plugin), but the second step should be to start setting up the app according to the instructions in the repository at https://github.com/pmusaraj/discourse-mobile-single-site-app
what is the system that connects player-id from Onesignal with userid in Discourse?
I searched but on my users list in Onesignal there is no data about the discourse user and in discourse I was not able to find any reference to the Onesignal user.