export 'default' (imported as 'classes') was not found in './modules/classes'

## **Describe the bug (required)** / **详细描述 bug（必填）**
ERROR in ./node_modules/@alilc/lowcode-engine/es/engine-core.js 145:11-18
export 'default' (imported as 'classes') was not found in './modules/classes' (possible exports: DocumentModel, History, InnerNode, Node, NodeChildren, Project, Prop, Selection, SettingPropEntry, SettingTopEntry, SimulatorHost, Skeleton, SkeletonItem)

A clear and concise description of what the bug is. / 请提供清晰且精确的 bug 描述

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## **To Reproduce (required)** / **如何复现 bug？（必填，非常重要）**

Steps to reproduce the behavior: / 详细复现步骤：

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English version example：
1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

中文版示例：
1. 打开 [demo](http://lowcode-engine.cn/demo)；
2. 点击标题；
3. 在右侧修改标题内容为「修改后的标题」；
4. 渲染画布标题组件没有更新显示为「修改后的标题」；

## **Expected behavior (required)** / **预期行为（必填，非常重要）**
A clear and concise description of what did you expect to happen. / 请清晰和精确的描述你预期的行为

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## **Screenshots (optional)** / **bug 截图（可选）**
Sceenshots for further information. (If applicable.) / 一些有用的截图将会帮助我们更好的明确以及定位问题

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## **Environments (please complete the following information) (required):** / **请提供如下信息（必填）**
- AliLowCodeEngine version: [e.g. 1.2.2] / 低代码引擎版本
- AliLowCodeEngineExt version: [e.g. 1.2.2] / 低代码引擎扩展包版本
- Browser [e.g. chrome, safari] / 浏览器版本
- materials / plugins / tools / 其他物料 / 插件 / 工具链版本

> (this information can be collected via [the manual plugin](https://img.alicdn.com/imgextra/i1/O1CN0115zonY1IsgbkZ2ir7_!!6000000000949-2-tps-3066-1650.png) / 版本信息可[通过低代码用户手册插件收集](https://img.alicdn.com/imgextra/i1/O1CN0115zonY1IsgbkZ2ir7_!!6000000000949-2-tps-3066-1650.png))

## **Additional context (optional)** / **更多额外信息（可选）**
Any other context of the problem here. / 可以追加更多的额外信息，帮助定位问题
我获取了github上的demo示例可以运行，但是当我将示例生成的schema和packages使用cra新项目打开加载就会出现错误。
运行方式按照官网给的使用渲染模块示例（https://lowcode-engine.cn/site/docs/guide/expand/runtime/renderer）。另外只渲染一个简单的button是可以成功的。我检查了network，显示packages都成功加载了
不知道是否是我使用不正确，请教一下如何能正确的在其他项目里渲染生成的json

Start with the CRA reproduction described in the issue and the runtime renderer guide, then inspect node_modules/@alilc/lowcode-engine/es/engine-core.js around line 145 and its ./modules/classes export. Verify the generated schema and packages against the case where a simple button renders successfully; done means the full schema renders without the missing-default-export error.

Written by the indexing model from the issue text.