X_PWA_SYNC_INCOMPLETE

the background-sync outbox flush left mutations queued

registered, thrown by nothing since 21.0.0, for the same reason as X_PWA_SYNC_FLUSH_FAILED: there is no flush endpoint to report remaining > 0. A queue left undrained stays in the page's IndexedDB and replays on the next load

delete any branch that matches this code, because it never runs. pwa.backgroundSync is a boolean, and the retry schedule is the browser Background Sync API's own