Incorrect output of CJS exports with explicit string names

[quantizor]

Example reproduction: https://replit.com/@probablyup/tsup-repro

I went deep and tested this in esbuild and rollup, I believe the odd behavior is coming from tsup.

Steps:

1. Fork the repro
2. Click Run
3. Go to dist/input.cjs.js

You'll see this output at the bottom which is invalid:

exports."design-system" = design_system;

It should be:

exports["design-system"] = design_system;

Additional replications:

• rollup
• esbuild

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