Error: The initialHeaders argument for Prerender must be an object with string key/values

[ivodevbr]

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
      Platform: linux
      Arch: x64
      Version: #42~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Apr 18 17:40:00 UTC 2
    Binaries:
      Node: 18.15.0
      npm: 9.5.0
      Yarn: 1.22.19
      pnpm: N/A
    Relevant packages:
      next: 13.4.1
      eslint-config-next: 13.4.1
      react: 18.2.0
      react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

Middleware / Edge (API routes, runtime)

Link to the code that reproduces this issue

npx create-next-app@latest // with typescript, eslint, tailwind src directory and @/* import,

To Reproduce

// latest version from 2023-may-06
  "dependencies": {
    "@types/node": "20.1.0", "@types/react": "18.2.6", "@types/react-dom": "18.2.4","autoprefixer": "10.4.14",
    "eslint": "8.40.0", "eslint-config-next": "13.4.1", "next": "13.4.1",
    "postcss": "8.4.23", "react": "18.2.0", "react-dom": "18.2.0", 
    "tailwindcss": "3.3.2", "typescript": "5.0.4"
  }

// project/src/app/example/cookie1/route.ts
import { NextResponse } from "next/server";

export async function GET(req: NextRequest) {
  const res = new NextResponse();
  res.cookies.set("theme", "light");
  res.cookies.set("my_company", "ACME");
  return res;
};

Describe the Bug

if you run

rm -rf .next && npm run build && npm run start

Its run ok, but if you deploy it at vercel you get this error.
Error: The initialHeaders argument for Prerender must be an object with string key/values

Maybe source of problem is this code:

https://github.com/vercel/vercel/blob/main/packages/build-utils/src/prerender.ts

// line 96
    if (initialHeaders !== undefined) {
      if (
        !initialHeaders ||
        typeof initialHeaders !== 'object' ||
        Object.entries(initialHeaders).some(
          ([key, value]) => typeof key !== 'string' || typeof value !== 'string'
        )
      ) {
        throw new Error(
          `The \`initialHeaders\` argument for \`Prerender\` must be an object with string key/values`
        );
      }
      this.initialHeaders = initialHeaders;
    }

Expected Behavior

It deploys with out error.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

Vercel

[ivodevbr]

Documentation about cookie in route.
https://nextjs.org/docs/app/api-reference/functions/next-response#setname-value

[github-actions]

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