Describe the bug

When composing a class from another file in CSS Modules, an error is not emitted if the class is not found.

This is akin to not erroring when trying to import a missing export from another JS file, and can lead to bugs.

This is fixed by #16018, but wanted to file it for tracking purposes since this seems like a pretty major issue that wasn't reported.

(Originally reported in privatenumber/vite-css-modules#2)

Reproduction

https://stackblitz.com/edit/vitejs-vite-w9i5ct?file=src%2Fstyle.module.css

Steps to reproduce

1. In style.modules.css, observe that large-text is imported from ./utils.module.css
2. In utils.module.css, observe that it's an empty file
3. In the DOM, observe that undefined is passed in as a class:
   

System Info

N/A

Used Package Manager

npm

Logs

No response

Validations

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• The provided reproduction is a minimal reproducible example of the bug.