`.css` file with same name results in empty `.js` output

[silverwind]

Reproduction link or steps

1. Clone https://github.com/silverwind/tsdown-multi
2. Run npm i && npx tsdown

What is expected?

That both dist/index.js and dist/index.css contain the bundled code.

What is actually happening?

dist/index.js is generated with 0 bytes because the entry index.css apparently generates a second empty index.js which unexpectedly overwrites the existing index.js:

ℹ tsdown v0.17.0-beta.5 powered by rolldown v1.0.0-beta.52
ℹ config file: /Users/silverwind/git/tsdown-multi/tsdown.config.ts
ℹ entry: index.css
ℹ Build start
ℹ dist/index.js   0.00 kB │ gzip: 0.02 kB
ℹ dist/index.css  0.02 kB │ gzip: 0.04 kB
ℹ 2 files, total: 0.02 kB
✔ Build complete in 9ms

Any additional comments?

The same entry file configuration works with vite and rollup. I recommend for .css files to not generate useless empty .js output files.