Предупреждение: React.createElement: тип недействителен - ожидается строка (для встроенных компонентов) или класс / функция (для составных компонентов)

Question

Приложение. js

import AccountScreen from './src/screens/AccountScreen'
import SignupScreen from './src/screens/SignupScreen'
import SigninScreen from './src/screens/SigninScreen'
import TrackCreateScreen from './src/screens/TrackCreateScreen'
import TrackDetailScreen from './src/screens/TrackDetailScreen'
import TrackListScreen from './src/screens/TrackListScreen'
import React from 'react'
import {createSwitchNavigator} from 'react-navigation'
import {createAppContainer} from 'react-navigation'
import {createStackNavigator} from 'react-navigation-stack'
import {createBottomTabNavigator} from 'react-navigation-tabs'
import {Provider as AuthProvider} from './src/context/AuthContext'

const switchNavigator = createSwitchNavigator({
  loginFlow: createStackNavigator({
    Signup: SignupScreen,
    Signin: SigninScreen
  }),
  mainFlow: createBottomTabNavigator({
    trackListFlow: createStackNavigator({
      TrackList: TrackListScreen,
      TrackDetail: TrackDetailScreen
    }),
    TrackCreate: TrackCreateScreen,
    Account: AccountScreen
  })
})

const App = createAppContainer(switchNavigator)

export default () => {
  return(
    <AuthProvider>
      <App/>
    </AuthProvider>
  )
}

Привет всем, я получаю следующие ошибки в этом React Native Code. Может кто-нибудь проверить и сообщить мне, если я что-то упустил или делаю что-то не так? Ниже приведены предупреждения и ошибки, которые я получаю.

Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: %s.%s%s, undefined,  You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

Check your code at App.js:33., 
    in _default (at withExpoRoot.js:26)
    in RootErrorBoundary (at withExpoRoot.js:25)       
    in ExpoRoot (at renderApplication.js:40)
    in RCTView (at AppContainer.js:101)
    in RCTView (at AppContainer.js:119)
    in AppContainer (at renderApplication.js:39)

Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

Check the render method of `_default`.

Warning: %s: Error boundaries should implement getDerivedStateFromError(). In that method, return a state update to display an error message or fallback UI., RootErrorBoundary

Answer 1

import {createSwitchNavigator} from 'react-navigation'
import {createAppContainer} from 'react-navigation'
import {createStackNavigator} from 'react-navigation-stack'
import {createBottomTabNavigator} from 'react-navigation-tabs'

Все ошибки и предупреждения были устранены путем удаления фигурных скобок из этих модулей импорта.

Было бы действительно замечательно, если бы кто-то мог дать лучший подход к этой проблеме.