expected "indent", got "eos" (Stylus)

Hey,

I'm currently using Stylus as a CSS preprocessor.

In the webpack.mix.js I used what was written in the doc:

mix.js('resources/js/app.js', 'public/js')
   .stylus('resources/stylus/app.styl', 'public/css');

And i got an app.styl stylus file which is importing an other stylus file called var.styl:

@import 'var'

But then in the watcher command prompt it display me this error:

ERROR in ./resources/stylus/app.styl
Module build failed: ModuleBuildError: Module build failed: ParseError: C:\Users\Lucas\Desktop\laravel\resources\stylus\var.styl:1:42
   1| test #fff
-----------------------------------------------^

expected "indent", got "eos"

Everything works fine if the stylus code is located in the app.styl file but I got this error for any other file i'm importing.

Is there a way to solve this problem ?