vue源码编译 waiting for changes

vue源码，
npm install，
npm run dev，
就这样一直卡着不动了

PS E:\vue\vue-code\vue> npm run dev

> vue@2.6.10 dev E:\vue\vue-code\vue
> rollup -w -c scripts/config.js --environment TARGET:web-full-dev

rollup v1.25.2
bundles E:\vue\vue-code\vue\src\platforms\web\entry-runtime-with-compiler.js → dist\vue.js...
created dist\vue.js in 2.1s

[2019-10-24 16:07:03] waiting for changes...

说明编译成功了，waiting for changes...是说，正在监听你的文件改动

https://coding.imooc.com/learn/questiondetail/73779.html

然后呢，想在源码里打个debugger,怎么弄，调试源码