Unhandled Rejection (SecurityError): The operation is insecure. On a fresh create-react-app project
Seems that the issue exists only in Firefox. Anyone still bugged by this bug can try disabling Delete cookies and site data when Firefox is closed option in Privacy and Security settings.
Or try wrapping the navigator.serviceWorker usages inside a try/catch. In my case
if ("serviceWorker" in navigator) { navigator.serviceWorker.ready .then(registration => { registration.unregister(); }) .catch(error => console.log("ServiceWorker Warning: ", error)); }