Not reproducible with dart-sass CLI:
$ npx dart-sass --load-path="./node_modules" fixture-import.scss
Reproducible when compiled using sass-loader (Webpack plugin):
$ npx webpack --config=webpack.config.js
Hash: bdf8ee812cf608b6e3a8
Version: webpack 4.41.5
Time: 318ms
Built at: 02/04/2020 10:09:49 AM
Asset Size Chunks Chunk Names
main.js 4.25 KiB main [emitted] main
Entrypoint main = main.js
[./fixture-import.scss] 434 bytes {main} [built] [failed] [1 error]
ERROR in ./fixture-import.scss
Module build failed (from ./node_modules/sass-loader/dist/cjs.js):
SassError: Can't find stylesheet to import.
╷
1 │ @forward "@material/base" as mdc-base-*;
│ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
╵
node_modules/@material/button/_mixins.import.scss 1:1 @import
/Users/abhiomkar/code/sass-bug-module/fixture-import.scss 1:9 root stylesheet
Changing webpack entry file fixture-import.scss => fixture-use.scss would fix the error.