React Native BUG(001)

Code ：

class runningProgram extends Component {    state = {        str_id: 'str_5km',        stringValue: stringList.str_5km.stringValue,        modelIndex: 0,    };    render() {        return <View>            <Text>Please choose the target for your plan:</Text>            <View>                <PickerIOS                    selectedValue={this.state.str_id}                    onValueChange= {(str_id) => this.setState({str_id, modelIndex: 0})} >                    {Object.keys(stringList).map((str_id) => (                        <PickerItemIOS                            key={str_id}                            value={str_id}                            label={stringList[str_id].stringValue}                        />                    ))}                </PickerIOS>            </View>        </View>;    }};

Should be:

Error：