Uncaught TypeError: (src_default.middleware ?? []) is not iterable about itty-router

[kwhitley]

What is it?

You’re seeing the wrangler dev issue, described here:
https://itty.dev/itty-router/guides/cloudflare-workers.

What you can do to fix

In your root/index file, destructure your router as part of your export. This strips the Proxy prototype that is intercepting Wrangler/Miniflare's request.

export default { ...router }

What you can do to help

Here's the issue filed with Wrangler team. Please go thumbs up or comment on this thread to spur things along.

What's happening (for the curious)

In local development, Wrangler has introduced a middleware property on the default export. The problem is, if they find it, they assume it's an array (of middleware) and immediately iterate it without any safety checks/validation.

In itty-router, we use a Proxy on the prototype chain to intercept unknown properties of routers and map them to route handlers with the given HTTP method. For instance, router.get maps to GET, router.foo to FOO, etc. So when we export the router directly (perfectly fine in most environments), and Wrangler asks for a middleware property, itty returns a route handler (a function). When you try to iterate a function, you get the error you've found.

[kwhitley]

Perfectly happy to, because I certainly doubt you'll be the last to discover it (until the Wrangler team sorts things out on their end).

[kwhitley]

The PR for this has been merged into main on Wrangler... just need to find the release that includes it:
cloudflare/workers-sdk#5420

[wqcstrong]

You’re seeing the wrangler dev issue, described here https://itty.dev/itty-router/guides/cloudflare-workers.

Good news is, this works fine in production as-is, or likely more helpful to you, you can destructure your export to solve this in local dev.

export default { ...router }

Thanks, the export default { ...router } is ok , maybe you can keep the issue opened for other user.