1.2.0 Error: Path must be a string. Received undefined under Nodejs 6

[immccc]

I can't get rid of this error when running the grunt contrib stylus task:

Running "stylus:files" (stylus) task
Verifying property stylus.files exists in config...OK
Files: resources/styles/general.styl
Options: banner="", compress, paths=["resources/styles"], relativeDest="out"
Warning: Path must be a string. Received undefined Use --force to continue.

Aborted due to warnings.

Behold the options currently defined in gruntfile.js:

        stylus: {
          options: {
            paths: ['resources/styles'],
            relativeDest: 'out'
          },
          files: {
            src: ['resources/styles/*.styl'],
            ext: '.css'
          }
        },

After realizing that I am not skipping anything required and looking for a response about this issue, I found that there is an open related issue: webpack/stylus-loader#115 , but the developers solved by its own project (which makes sense after all)