无法编译 src\App.js Line 66:12: 'oldstate' is not defined no-undef

Question

'App.js' 代码

还有其他几个不同的文件，所以如果有人需要查看文件结构，请告诉我。

import React from 'react';
import CoinList from './components/CoinList/CoinList';
import AccountBalance from './components/AccountBalance/AccountBalance';
import styled from 'styled-components';
import ExchangeHeader from './components/ExchangeHeader/ExchangeHeader';

const Div = styled.div`
 text-align: center;
 background-color: #373c46;
color: rgba(255, 255, 255, 0.842);
`;

class App extends React.Component {
    constructor(props) {
        super(props)
        this.handleRefresh = this.handleRefresh.bind(this);
        this.state = {
            balance: 10000,
            showBalance: true,
            coinData: [
                {
                    name: 'Bitcoin',
                    ticker: 'BTC',
                    balance: 1.5,
                    price: 9999.99
                },
                {
                    name: 'Ethereum',
                    ticker: 'ETH',
                    balance: 32.0,
                    price: 299.99
                },
                {
                    name: 'Tether',
                    ticker: 'USDT',
                    balance: 0,
                    price: 1.0
                },
                {
                    name: 'Ripple',
                    ticker: 'XRP',
                    balance: 1000,
                    price: 0.2
                },
                {
                    name: 'Bitcoin Cash',
                    ticker: 'BCH',
                    balance: 10,
                    price: 298.99
                },
                {
                    name: 'Cardano',
                    ticker: 'ADA',
                    balance: 20,
                    price: 1.56
                },
            ]
        }
        this.handleRefresh = this.handleRefresh.bind(this);
        this.handleBalanceVisibilityChange = this.handleBalanceVisibilityChange.bind(this);

    };

    handleBalanceVisibilityChange() {
        this.setState(function (oldState) {
            return {
                ...oldstate,
                showBalance: !oldState.showBalance
            }
        });
    }

    handleRefresh(valueChangeTicker) {
        const newCoinData = this.state.coinData.map(
            function ({ticker, name, price}) {
                let newPrice = price
                if (valueChangeTicker === ticker) {

                    const randomPercentage = 0.995 + Math.random() * 0.01
                    newPrice = newPrice * randomPercentage
                }
                return {
                    name,
                    ticker,
                    price: newPrice
                }
            });
        this.setState({coinData: newCoinData});
    }

    render() {
        return (
            <Div className="App">
                <ExchangeHeader/>
                <AccountBalance
                    amount={this.state.balance}
                    showBalance={this.state.showBalance}
                    handleBalanceVisibilityChange={this.handleBalanceVisibilityChange}/>
                <CoinList
                    coinData={this.state.coinData}
                    showBalance={this.state.showBalance}
                    handleRefresh={this.handleRefresh}/>
            </Div>
        )
    }
}

export default App;

我不确定如何解决此错误。我正在学习 React 的课程，它是几年前制作的，所以我认为可能与更新有关。

我也尝试了多种解决方案，但还是遇到了同样的问题。有人可以帮忙吗？