ServiceWorker is not defined error #41
Description
Got a report of a "ServiceWorker is not defined" error. Not sure in which contexts where ServiceWorker can be undefined, but we should check if it's undefined before checking an instanceof to make sure we don't hit this error:
deephaven-ipywidgets/src/widget.ts
Line 120 in 5229be7
Looks like ServiceWorker is only defined in a SecureContext. If you go to http://example.com/ for example, check the browser console and ServiceWorker is undefined there. We should check this and handle it.