fix: remove value and writable properties from headers descriptor

[avanderbergh]

Fixes #12548

• Ensure that any existing value and writable properties are deleted from the headers descriptor before adding getters and setters.
• This prevents the error: Invalid property descriptor. Cannot both specify accessors and a value or writable attribute, #<Object>

Changes

• Removed the value and writable properties from the headers descriptor before defining getters and setters for the headers property on the Request object.
• Updated the Object.defineProperty call to prevent the Invalid property descriptor error during prerendering.
• Added a setter to request.headers to allow updating _headers if needed.

Testing

This change was tested by building the Astro project with prerender = true and confirming that the build completes without the Invalid property descriptor error.

No automated tests have been added since this affects the internal build handling of the Request headers property, but manual testing confirms the fix.

Docs

No documentation changes are needed for this fix, as this is an internal implementation detail that does not affect user-facing API or behavior directly.

/cc @withastro/maintainers-docs for feedback if required.

[changeset-bot]

🦋 Changeset detected

Latest commit: 82a13d0

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[codspeed-hq]

CodSpeed Performance Report

Merging #12552 will degrade performances by 35.68%

_{Comparing avanderbergh:issue12548 (82a13d0) with main (97f413f)}

Summary

⚡ 1 improvements
❌ 1 regressions
✅ 4 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	avanderbergh:issue12548	Change
⚡	Rendering: streaming [false], .astro file	1.7 s	1.5 s	+15.47%
❌	Rendering: streaming [false], .md file	14.5 ms	22.5 ms	-35.68%

[bluwy]

Thanks for fixing this!

[avanderbergh]

@bluwy Hey, I just fixed a merge conflict by rebasing on main, hope that's the right way...

Does it need a new approval now? 😅

[bluwy]

No problem. LGTM!

[avanderbergh]

Thank you! 🙌🏻