What does SplashScreen is hidden mean?

I have come across this error [Unhandled promise rejection: Error: Native splash screen is already hidden. Call this method before rendering any view.]

Not sure why this is happening but I just want to fix this before I continue.

My App.js:

in App (created by ExpoRoot)
in ExpoRoot (at renderApplication.js:45)
in RCTView (at View.js:34)
in View (at AppContainer.js:106)
in DevAppContainer (at AppContainer.js:121)
in RCTView (at View.js:34)
in View (at AppContainer.js:132)
in AppContainer (at renderApplication.js:39)

This is my App.js

import { StatusBar } from 'expo-status-bar';
import React from 'react';
import { render } from 'react-dom';
import { Button, StyleSheet, Text, View } from 'react-native';
import AppNavigator from './src/navigation/Navigator';
import * as Font from 'expo-font';
import { AppLoading } from 'expo-app-loading';

export default class App extends React.Component {
  state = {
    isFontLoaded: false
  };

  async componentDidMount() {
    await Font.loadAsync({
      SemiBold: require('./src/fonts/Montserrat-Regular.ttf'),
      Medium: require('./src/fonts/Montserrat-Medium.ttf'),
      Regular: require('./src/fonts/Montserrat-Regular.ttf')
    });
    this.setState({ isFontLoaded: true });
  }

  render() {
    if (!this.state.isFontLoaded) {
      return <AppLoading />;
    }

    return <AppNavigator />;
  }
}

Please tell me how to fix this.