react路由懶加，項目經常上線導致沒有刷新的用戶出現js文件加載失敗： ChunkLoadError: Loading chunk 42 failed.

解決方案：

使用錯誤邊界：

import React, { Component } from 'react'

//錯誤邊界
//https://zh-hans.reactjs.org/docs/error-boundaries.html#gatsby-focus-wrapper
export default class ErrorBoundary extends Component {
  constructor(props) {
    super(props);
    this.state = { error: null, errorInfo: null };
  }
  
  componentDidCatch(error, errorInfo) {
    // Catch errors in any components below and re-render with error message
    this.setState({
      error: error,
      errorInfo: errorInfo
    })
    // You can also log error messages to an error reporting service here
  }
  
  render() {
    if (this.state.errorInfo) {
      // Error path
      return (
        <div className="m-error-wrap">
          <div className="m-error-img-wrap">
            <div className="m-error-img"></div>
          </div>
          <div className="m-error-text">網頁出錯了，請嘗試刷新一下~</div>
          <details style={{ whiteSpace: 'pre-wrap' }}>
            {this.state.error && this.state.error.toString()}
            <br />
            {this.state.errorInfo.componentStack}
          </details>
        </div>
      );
    }
    // Normally, just render children
    return this.props.children;
  }  
}