Doesn't work with `ember-cli-sass`

[villander]

Ember-cli: 3.28.0
ember-css-modules: 1.5.0

I have an addon that expose bootstrap CSS using the hook treeForStyles and my addon has a scss file named ember-odyssey.scss on addon-name/app/styles to be imported in the consumer app to bring the those styles. Which means I opted to use the alternative addon usage

Now I added ember-css-modules to have the scoped CSS for my components, and I followed the Addon Usage in the README adding the .placeholder file and addon.scss file:

And put an include path to my sass files:

// my-addon/index.ts
options: {
   cssModules: {
     extension: 'scss',
     intermediateOutputPath: '_modules.scss'
   }
 }

https://github.com/salsify/ember-css-modules/blob/master/docs/PREPROCESSORS.md#modules-and-preprocessor-syntax-in-isolation

The output is:

Build Error (SassCompiler)

File not found: /app/styles/app.scss
in any of the following include paths:
  /var/folders/0v/jpdg1flj3qscvbvt728pgt8c0000gn/T/broccoli-167747o1QM182GSfj/out-179-simple_concat_concat


Stack Trace and Error Report: /var/folders/0v/jpdg1flj3qscvbvt728pgt8c0000gn/T/error.dump.0cde3e4f99e53614db8fc427095a1792.log

What I'm doing wrong here?

cc: @dfreeman