Build fails with Invalid property descriptor when using Cloudflare adapter with modified Request headers prototype

[avanderbergh]

Astro Info

Astro                    v4.16.16
Node                     v20.18.0
System                   Linux (x64)
Package Manager          pnpm
Output                   server
Adapter                  @astrojs/cloudflare
Integrations             none

If this issue only occurs in one browser, which browser is a problem?

No response

Describe the Bug

When using the Cloudflare adapter in an Astro project, importing certain plugins (such as better-auth/plugins) results in an unexpected modification of the Request prototype.

Specifically, the Request.headers object is extended with a map property. This modification causes a build error during prerendering (astro build with export const prerender = true), resulting in the following error message:

Invalid property descriptor. Cannot both specify accessors and a value or writable attribute, #<Object>

The error is thrown in the /core/request file, when attempting to redefine the headers property of the Request object.

const request = new Request(url, {
	method: method,
	headers: headersObj,
	// body is made available only if the request is for a page that will be on-demand rendered
	body: staticLike ? null : body,
});

if (staticLike) {
	// Warn when accessing headers in SSG mode
	const _headers = request.headers;
	const headersDesc = Object.getOwnPropertyDescriptor(request, 'headers') || {};
	Object.defineProperty(request, 'headers', {
		...headersDesc,
		get() {
			logger.warn(
				null,
				`\`Astro.request.headers\` is unavailable in "static" output mode, and in prerendered pages within "hybrid" and "server" output modes. If you need access to request headers, make sure that \`output\` is configured as either \`"server"\` or \`output: "hybrid"\` in your config file, and that the page accessing the headers is rendered on-demand.`,
			);
			return _headers;
		},
	});
} else if (clientAddress) {
	// clientAddress is stored to be read by RenderContext, only if the request is for a page that will be on-demand rendered
	Reflect.set(request, clientAddressSymbol, clientAddress);
}

The issue arises because the headers property already has a value, and the build logic tries to add a getter to it in order to show a warning when accessing the headers. This combination of both having a value and adding a getter causes the Invalid property descriptor error, resulting in the build failing.

For additional details, please refer to the related issue I created in the better-auth repository: better-auth issue #681.

What's the expected result?

The build completes without errors.

Link to Minimal Reproducible Example

https://github.com/avanderbergh/better-auth-astro-issue

Participation

• I am willing to submit a pull request for this issue.