This case should just be passed directly to the parent handler

It would very useful to add a field to see when an error happened for the first time, specially useful when you have an outage.

as suggested by @dcramer in https://github.com/getsentry/sentry/pull/16116/files#diff-aa34cb9acf9a36938078d3c80d01a25a
it might be a good pattern to mock sentry TOGETHER with the testkit

jest.mock('@sentry/browser', () => {
    ...Sentry,
   testkit,
   init: options =>
       SentryBrowser.init({ ...options, transport: sentryTransport  })
})