message: [TypeScript] Import fetch polyfill type declaration.
diff: -import { fetch, NativeModules } from 'react-native'
  +import { NativeModules } from 'react-native'
  const Emission = NativeModules.Emission || {}
  +declare const fetch: ReactNative.fetch
  import { metaphysicsURL } from './relay/config'
  import { NetworkError } from './system/errors'
  