react-custom-scrollbar不适用于SpringScrollbar

Question

我遵循documentation来实现react-custom-scrollbar的SpringScollbars。 SpringScrollbars代码中有一个导入

import { SpringSystem, MathUtil } from 'rebound';

在这一行中，SpringSystem已正确导入，但MathUtil未正确导入。我怀疑由于这个问题，只有我的代码无法正常工作

在上图中，可以看出MathUtil没有被导入。有什么解决办法吗？

这是SpringScrollbars.js的代码

SpringScrollbars.js

import React, { Component } from 'react';
import { Scrollbars } from 'react-custom-scrollbars';
import { SpringSystem, MathUtil } from 'rebound';


export default class SpringScrollbars extends Component {

    constructor(props, ...rest) {
        super(props, ...rest);
        this.handleSpringUpdate = this.handleSpringUpdate.bind(this);
    }

    componentDidMount() {
        this.springSystem = new SpringSystem();
        this.spring = this.springSystem.createSpring();
        this.spring.addListener({ onSpringUpdate: this.handleSpringUpdate });
    }

    componentWillUnmount() {
        this.springSystem.deregisterSpring(this.spring);
        this.springSystem.removeAllListeners();
        this.springSystem = undefined;
        this.spring.destroy();
        this.spring = undefined;
    }

    getScrollTop() {
        return this.refs.scrollbars.getScrollTop();
    }

    getScrollHeight() {
        return this.refs.scrollbars.getScrollHeight();
    }

    getHeight() {
        return this.refs.scrollbars.getHeight();
    }

    scrollTop(top) {
        const { scrollbars } = this.refs;
        const scrollTop = scrollbars.getScrollTop();
        const scrollHeight = scrollbars.getScrollHeight();
        const val =  MathUtil.mapValueInRange(top, 0, scrollHeight, scrollHeight * 0.2, scrollHeight * 0.8);
        this.spring.setCurrentValue(scrollTop).setAtRest();
        this.spring.setEndValue(val);
    }

    handleSpringUpdate(spring) {
        const { scrollbars } = this.refs;
        const val = spring.getCurrentValue();
        scrollbars.scrollTop(val);
    }

    render() {
        return (
            <Scrollbars
                {...this.props}
                ref="scrollbars"/>
        );
    }
}