SvelteKit Auth, (Google), TypeError ("response" must be an instance of Response)

Provider type

Google

Environment

Environment

System:

• OS: Windows 10 10.0.22621
• CPU: (16) x64 AMD Ryzen 7 5800H with Radeon Graphics
• Memory: 4.44 GB / 15.35 GB
  Binaries:
• Node: 18.12.1 - C:\Program Files\nodejs\node.EXE
• Yarn: 1.22.19 - C:\Program Files\nodejs\yarn.CMD
• npm: 8.19.2 - C:\Program Files\nodejs\npm.CMD
• pnpm: 7.17.1 - C:\Program Files\nodejs\pnpm.CMD
  Browsers:
• Edge: Chromium (118.0.2088.61)
• Internet Explorer: 11.0.22621.1

Reproduction URL

https://github.com/notarib-catcher/fest-msite-sveltk

Describe the issue

I am hosting my sveltekit site on Vercel's Hobby plan, we're using authjs for sveltekit with google as the provider to authenticate users.
The version of Authjs I'm using in live is @auth/sveltekit 0.3.10, the error is occuring even when I update to 0.3.11 (latest)
The error seems to be a TypeError that occurs when attempting to login.
So far, I have only attempted this with the google auth provider.

To be completely honest, I am at a loss for why this error is occuring.

• The error only occurs on live production and not on dev deployments - Login works fine on dev
• I am unable to reproduce it on the local dev server (vite dev)
• The error came up without intervention: We made a new deployment with CSS and some text changes that triggered it
• The error seems to have come up after the vercel incident last night (Degraded performance: Assigning domains) however, this may also be coincidence.

How to reproduce

Since this error is rather specific to my deployment, I cannot provide a proper steps-to-reproduce, however here is the error log from vercel's runtime logs

[POST] /auth/signin/google

[auth][cause]: TypeError: "response" must be an instance of Response
    at Module.processDiscoveryResponse (file:///var/task/node_modules/oauth4webapi/build/index.js:212:15)
    at getAuthorizationUrl (file:///var/task/node_modules/@auth/core/lib/oauth/authorization-url.js:19:28)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async Module.signin (file:///var/task/node_modules/@auth/core/lib/routes/signin.js:15:20)
    at async AuthInternal (file:///var/task/node_modules/@auth/core/lib/index.js:112:36)
    at async Auth (file:///var/task/node_modules/@auth/core/index.js:100:30)
    at async respond (file:///var/task/.svelte-kit/output/server/index.js:2523:22)
    at async Server.default (file:///var/task/.svelte-kit/vercel-tmp/index.js:47:3)
    at async Server.<anonymous> (/var/task/___vc/__launcher/__launcher.js:14:11367)

[auth][details]: {
  "provider": "google"
}

[auth][error][SignInError]: Read more at https://errors.authjs.dev#signinerror

Expected behavior

The user should be signed in with google

Start with the Vercel runtime stack trace, especially oauth4webapi/build/index.js and @auth/core/lib/oauth/authorization-url.js, then compare the production and development environments around Google sign-in. The issue is resolved when the production SvelteKit deployment completes Google authentication without the Response TypeError.