in workbox-v4.3.1/workbox-background-sync.dev.js [655:667]
async registerSync() {
if ('sync' in registration) {
try {
await registration.sync.register(`${TAG_PREFIX}:${this._name}`);
} catch (err) {
// This means the registration failed for some reason, possibly due to
// the user disabling it.
{
logger_mjs.logger.warn(`Unable to register sync event for '${this._name}'.`, err);
}
}
}
}