[Bug Report] 使用命令行主题工具自定主题出错

### Element UI version
2.13.1

### OS/Browsers version
windows10

### Vue version
3.0.0-alpha.13

### Reproduction Link

### Steps to reproduce
1、全局安装 `npm i element-theme -g `
2、项目安装`npm i element-theme-chalk -D`，版本号2.13.1
`node`版本号 v12.13.1
3、执行 `et -1`命令
4、结果：
报错
`fs.js:27
const { Math, Object } = primordials;
^
ReferenceError: primordials is not defined`

### What is Expected?
正常生成 `element-variables.scss`文件

### What is actually happening?
报错
`fs.js:27
const { Math, Object } = primordials;
^
ReferenceError: primordials is not defined`