出现“无法读取未定义属性'setImmediate'的类型错误”通常是由于在使用Angular9 DHX Spreadsheet时缺少必要的依赖项或配置错误导致的。以下是一些可能的解决方法：

1. 确保已正确安装了所需的依赖项：
   • 在项目根目录下运行npm install dhtmlx-spreadsheet-pro命令以安装DHX Spreadsheet。
   • 确保已在angular.json文件的scripts数组中引入了相关的dhtmlx样式文件和脚本文件：

"scripts": [
  "node_modules/dhtmlx-spreadsheet-pro/codebase/spreadsheet.js",
  "node_modules/dhtmlx-spreadsheet-pro/codebase/spreadsheet.css"
]

2. 确保已正确配置了DHX Spreadsheet模块：
   • 在使用DHX Spreadsheet的组件中，确保已正确导入和初始化dhxSpreadsheet模块：

import { Component, ViewChild, AfterViewInit } from '@angular/core';
import { DhxSpreadsheetComponent } from 'dhx-angular';

@Component({
  selector: 'app-spreadsheet',
  template: ''
})
export class SpreadsheetComponent implements AfterViewInit {
  @ViewChild('spreadsheet', { static: false }) spreadsheet: DhxSpreadsheetComponent;

  ngAfterViewInit() {
    this.spreadsheet.detail_setImmediate = (callback: any) => {
      setTimeout(callback, 0);
    };
    this.spreadsheet.detail_clearImmediate = (id: any) => {
      clearTimeout(id);
    };
    this.spreadsheet.detail_setTimeout = (handler: any, timeout?: any) => {
      return timeout ? setTimeout(handler, timeout) : setTimeout(handler);
    };
    this.spreadsheet.detail_clearTimeout = (id: any) => {
      clearTimeout(id);
    };
    this.spreadsheet.detail_requestAnimationFrame = (callback: any) => {
      return requestAnimationFrame(callback);
    };
    this.spreadsheet.detail_cancelAnimationFrame = (id: any) => {
      cancelAnimationFrame(id);
    };
  }
}

3. 如果以上解决方法仍然无效，可以尝试将DHX Spreadsheet升级到最新版本。

请注意，DHX Spreadsheet是一个商业产品，您需要购买许可证才能在生产环境中使用它。以上解决方法假设您已正确购买和配置了DHX Spreadsheet。