[Vercel] Setting headers fails on Node18 Fetch API Response

[shishkin]

What version of astro are you using?

1.6.10

Are you using an SSR adapter? If so, which one?

Vercel

What package manager are you using?

yarn

What operating system are you using?

Linux

Describe the Bug

Node 18 introduced Fetch API Response. When using it with Astro on Vercel, it fails with error:

{
  "errorType": "Runtime.UnhandledPromiseRejection",
  "errorMessage": "TypeError: response.headers.raw is not a function",
  "reason": {
    "errorType": "TypeError",
    "errorMessage": "response.headers.raw is not a function",
    "stack": [
      "TypeError: response.headers.raw is not a function",
      "    at setResponse (file:///var/task/node_modules/@astrojs/vercel/dist/serverless/request-transform.js:61:46)",
      "    at Server.handler (file:///var/task/node_modules/@astrojs/vercel/dist/serverless/entrypoint.js:22:11)",
      "    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)"
    ]
  },
  "promise": {},
  "stack": [
    "Runtime.UnhandledPromiseRejection: TypeError: response.headers.raw is not a function",
    "    at process.<anonymous> (file:///var/runtime/index.mjs:1194:17)",
    "    at process.emit (node:events:525:35)",
    "    at process.emit (node:domain:489:12)",
    "    at emit (node:internal/process/promises:149:20)",
    "    at processPromiseRejections (node:internal/process/promises:283:27)",
    "    at process.processTicksAndRejections (node:internal/process/task_queues:96:32)"
  ]
}

This is likely due to Vercel adapter using headers.raw(), not available on the Web API Headers class.

Is there a reason .raw() call is required?

Link to Minimal Reproducible Example

TBD

Participation

• I am willing to submit a pull request for this issue.

[shishkin]

Potentially duplicate of #5461

[bluwy]

Yeah this is a duplicate of #5461