localizeHref can't run on edge functions runtime (Deno)

[Wituareard]

...because "window" is present and so it tries to access "window.location.href". I tried to resolve the stacktrace from #538 and this is what I got:

TypeError: Cannot read properties of undefined (reading 'href')
  at C4 (../../src/lib/paraglide/runtime.js:300:54)
  at setLocale (../../src/lib/paraglide/runtime.js:183:16)
  at getLocale (../../src/lib/paraglide/runtime.js:1155:26)
  at localizeHref (../../src/lib/components/navbar/universal/UniversalNavbar.svelte:11:19)
  at fn (../../node_modules/.pnpm/svelte@4.2.20/node_modules/svelte/src/runtime/internal/ssr.js:134:15)
  at <anonymous> (../../src/lib/components/navbar/universal/UniversalNavbar.svelte:25:30)
  at fn (../../node_modules/.pnpm/svelte@4.2.20/node_modules/svelte/src/runtime/internal/ssr.js:134:15)
  at $$props (../../src/lib/components/navbar/Navbar.svelte:6:21)
  at fn (../../node_modules/.pnpm/svelte@4.2.20/node_modules/svelte/src/runtime/internal/ssr.js:134:15)
  at $$props (../../src/routes/header.svelte:12:21)

I think the function names are off by one line.

[anthonybailey]

This is good work Nils and mostly aligns with my memory of findings.

Please note: it is critical when doing these investigations to really, really pin down your testing mechanism.

Things I have run into:

Netlify have historically run quite an old Deno version.

Netlify CLI can act slightly differently to Netlify production wrt to many things. Edge functions, serverless functions and Deno usage. "netlify serve" and "netlify dev" similarly differ.

Pre-rendering matters lots. The logic by which SvelteKit decides which pages are pre-rendered can be surprising (e.g. reachability from other pages) and our attempts to play with some innards during build have often been more trouble than worth.

Netlify production needs a file to exist under a route to serve that route at all. The content of the file can be irrelevant to what is served in some cases (I think some pre-rendering, and definitely some edge and serverless functions.)

I haven't seen any difference in these routing matters between true production and previews wrapped with the Netlify Collaborate layer but would be completely unsurprised if some manifest.

[Wituareard]

it is critical when doing these investigations to really, really pin down your testing mechanism.

The original unresolved stack trace is just taken from the edge function log for the deploy preview.

The logic by which SvelteKit decides which pages are pre-rendered can be surprising (e.g. reachability from other pages)

We have configured SvelteKit to prerender all pages by default (in +layout.ts), so if the crawler can reach pages or knows them from the file structure, they will be prerendered.

Netlify production needs a file to exist under a route to serve that route at all.

I'm pretty sure that edge functions can handle arbitrary requests. The 404 is also generated by SvelteKit. However, it's possible that SvelteKit rejects requests for routes it doesn't know by default or something like that

[anthonybailey]

I'm unsure about a lot of this. Just saying to expect to be surprised. It may be relevant that with current settings we have one huge edge function, megabytes in size. Definitely reproduced locally a circumstance I believe we saw in prod, where after a few calls particular instances had their "render" edge function get into trouble, and then whether production site saw a 500 wrapping a 404 on some routes was down to which instance your request got routed to. Waves hands apologetically.

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On Sat, 8 Nov 2025, 14:51 Wituareard, ***@***.***> wrote: *Wituareard* left a comment (PauseAI/pauseai-website#540) <#540 (comment)> it is critical when doing these investigations to really, really pin down your testing mechanism. The stack trace is just taken from the edge function log for the deploy preview. it is critical when doing these investigations to really, really pin down your testing mechanism. We have configured SvelteKit to prerender all pages by default, so if the crawler can reach pages or knows them from the file structure, they will be prerendered. Netlify production needs a file to exist under a route to serve that route at all. I'm pretty sure that edge functions can handle arbitrary requests. The 404 is also generated by SvelteKit. — Reply to this email directly, view it on GitHub <#540 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAXXDIDXQGOJ3WLN2VYNL333X7NBAVCNFSM6AAAAACLQ2Q6X6VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTKMBWGYYDSOJSGY> . You are receiving this because you commented.Message ID: ***@***.***>

[Wituareard]

Can we close this?

[anthonybailey]

#548 was our fix.