An Webpack Error

你好，我是您的读者，在运行第四章源码 报以下错：

```
ERROR in Cannot find module 'escope'
 @ multi app

ERROR in Path must be a string. Received undefined
```

命令执行顺序：
```
npm i 
npm run build
npm run dev  //(改成了127.0.0.1)
```

未找到原因，能否帮忙解答下~