I'm trying to deploy my Next.js app using the App Router and pnpm to GitHub Pages, but I'm getting errors. Here's my setup:

### next.config.mjs:

/** @type {import('next').NextConfig} */
const nextConfig = {
  output: "export",
  images: {
    unoptimized: true,
  },
};

export default nextConfig;

### nextjs.yml (GitHub Actions workflow):

name: Deploy Next.js site to Pages

on:
  push:
    branches: ["main"]
  workflow_dispatch:

permissions:
  contents: read
  pages: write
  id-token: write

concurrency:
  group: "pages"
  cancel-in-progress: false

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: "lts/*"

      - name: Install pnpm
        run: |
          npm install -g pnpm

      - name: Setup Pages
        uses: actions/configure-pages@v4

      - name: Restore cache
        uses: actions/cache@v4
        with:
          path: |
            .next/cache
            node_modules
          key: ${{ runner.os }}-pnpm-${{ hashFiles('pnpm-lock.yaml') }}-${{ hashFiles('**.[jt]s', '**.[jt]sx') }}
          restore-keys: |
            ${{ runner.os }}-pnpm-${{ hashFiles('pnpm-lock.yaml') }}-

      - name: Install dependencies
        run: pnpm install

      - name: Build with Next.js
        run: pnpm next build

      - name: Upload artifact
        uses: actions/upload-pages-artifact@v3
        with:
          path: ./out

  deploy:
    environment:
      name: github-pages
      url: ${{ steps.deployment.outputs.page_url }}
    runs-on: ubuntu-latest
    needs: build
    steps:
      - name: Deploy to GitHub Pages
        id: deployment
        uses: actions/deploy-pages@v4

Even with this setup, it's throwing errors during deployment also the css isn't working!