这样操作

import  'assets/stylus/index.styl';

报错

 ERROR  Failed to compile with 1 errors                                                                                                                            
 This dependency was not found:
* assets/stylus/index.styl in ./src/main.js
To install it, you can run: npm install --save assets/stylus/index.styl

确定stylus-loade已经安装，使用的是vue-cli脚手架开发，但出错了