如何修复超出范围索引NaN的获取帧？在本地反应

Question

import React from "react";
    import {
    StyleSheet,
    View,
    ActivityIndicator,
    FlatList,
    Text,
    TouchableOpacity,
    ScrollView
    } from "react-native";
    export default class Source extends React.Component {
    static navigationOptions = ({ navigation }) => {
    return {
      title: "Source Listing",
      headerStyle: {backgroundColor: "#fff"},
      headerTitleStyle: {textAlign: "center",flex: 1}
     };
    };
    constructor(props) {
     super(props);
     this.state = {
       loading: true,
       dataSource:[]
      };
    }
    componentDidMount(){
    fetch("https://sgocr1.ankiti.com/a5a/hapi/app.pressmonitor.com/main/orders")
    .then(response => response.json())
    .then((responseJson)=> {
      this.setState({
       loading: false,
       dataSource: responseJson
      })
    })
    .catch(error=>console.log(error)) 
    }
    FlatListItemSeparator = () => {
    return (
      <View style={{
         height: .5,
         width:"100%",
         backgroundColor:"rgba(0,0,0,0.5)",
    }}
    />
    );
    }
    renderItem=(data)=>
    <TouchableOpacity style={styles.list}>
    <Text style={styles.lightText}>{data.item.item_title}</Text>


    </TouchableOpacity>
    render(){
     if(this.state.loading){
      return( 
        <View style={styles.loader}> 
          <ActivityIndicator size="large" color="#0c9"/>
        </View>
    )}
    return(
     <View style={styles.container}>
     { <FlatList
        data= {this.state.dataSource}
        ItemSeparatorComponent = {this.FlatListItemSeparator}
        renderItem= {item=> this.renderItem(item)}
        keyExtractor= {item=>item.id.toString()}
     /> }

    </View>

    )}
    }
    const styles = StyleSheet.create({
      container: {
        flex: 1,
        backgroundColor: "#fff"
       },
      loader:{
        flex: 1,
        justifyContent: "center",
        alignItems: "center",
        backgroundColor: "#fff"
       },
      list:{
        paddingVertical: 4,
        margin: 5,
        backgroundColor: "#fff"
       }
    });