SvelteKit fails to build if user provides default error page

[benmccann]

Describe the bug

A user reported that their project is failing when they run npm run build. I did some preliminary investigation and found that it's failing because it can't find the default error page in the manifest. If I delete src/routes/error.svelte from their project then the build passes. I guess Vite doesn't see the default error page being used or imported anywhere in this case

Reproduction

https://github.com/deozza/appquarium-admin-sveltekit

I made a fork which runs the latest SvelteKit and get the same issue: https://github.com/benmccann/appquarium-admin-sveltekit

Logs

build-server is generating the error:

> Cannot read property 'file' of undefined

System Info

latest

Severity

blocking all usage of SvelteKit

Additional Information

No response