元素类型无效，应为字符串

Question

我已将应用程序升级到SDK 35，并出现以下错误：

  

元素类型无效，预期为字符串

import { createStackNavigator, createAppContainer, createDrawerNavigator } from 'react-navigation';
import Start from './screens/Start.js'
const RootStack = createStackNavigator({
    Start: {
        screen: Start
    },
 });
const App = createAppContainer(RootStack);
export default App;