msw/test/browser/msw-api/setup-worker/start/on-unhandled-request/default.mocks.ts

import { http, HttpResponse } from 'msw'
import { setupWorker } from 'msw/browser'

const worker = setupWorker(
  http.get('/user', () => {
    return HttpResponse.json({ firstName: 'John' })
  }),
)

// By default any unhandled requests are performed as-is
// but produce warnings.
worker.start()