`Request` object passed through AutoRouter cannot be `fetch`ed in Cloudflare Workers

[zlepper]

Describe the Issue

I have a cloudflare worker that intercepts some routes, and just forwards all other routes to the origin. I believe this worked when i wrote the code originally, however it seems to have started failing when i picked up the project again earlier today.

Example Router Code

import { AutoRouter, Router } from 'itty-router';

const router = AutoRouter();

router.all('*', async (req) => {
	try {
		return await fetch(req);
	} catch (e) {
		console.error(e);
		return new Response('proxy request failed');
	}
});


export default {
	async fetch(request, env, ctx) {

		const u = new URL(request.url);
		u.host = 'example.com';
		u.port = '';
		u.protocol = 'https';

		const changedRequest = new Request(u, request);

		if (u.searchParams.get('skip')) {
			console.log('fetching directly');
			return await fetch(changedRequest);
		}

		console.log('fetching through itty-router');
		return router.fetch(changedRequest, env, ctx);
	}
};

Request Details

GET http://localhost:8787 GET http://localhost:8787?skip=true

Steps to Reproduce

The minimal example just proxies all requests to example.com. If you start this in wrangler and invoke http://localhost:8787?skip=true it works fine. (This skips itty-router and just forwards the request directly). If you do not pass skip=true by just invoking http://localhost:8787 then it will fail with TypeError: Invalid URL: [object Request].

If you switch to the normal Router then it also works fine.

Expected Behavior

Cloudflare forwards the request without issues.

Actual Behavior

TypeError: Invalid URL: [object Request] (In the minimal example, compatibility_date="2024-12-30") or TypeError: Fetch API cannot load: [object Object] (In my original code, compatibility_date="2023-09-18")

Environment (please complete the following information):

• Environment: Cloudflare Workers
• itty-router Version: 5.0.18
• Other Relevant Libraries and their versions:
  • Wrangler: 3.99.0

Additional Context

The issue seems to not occur when using Router directly. Tracing the issue this seems to be caused by withParams wrapping the request object in a Proxy, which Cloudflare cannot handle.

As a workaround i can initialize a new request object and copy over relevant properties, however this is a bit of a wack-a-mole as i have to make sure to do it in all places i fall back to just forwarding the original request.