【Netlify】ビルド時にエラーが発生する

Question

前提

NetlifyにNext.jsで作成したプロジェクトをデプロイしています。

実現したいこと

next-sitemapでサイトマップを作成したく、例えば下記のURLのようにやってみているのですが、
Netlifyで『next build』以外を指定すると ビルドエラーとなってしまいます。
『next build』だとエラーは出ませんが、サイトマップは作成されません。
https://fwywd.com/tech/next-sitemap

どのようにしたらサイトマップが作成され、デプロイも行われるでしょうか？

発生している問題・エラーメッセージ

────────────────────────────────────────────────────────────────
   Netlify Build
 ────────────────────────────────────────────────────────────────
 ​
 ❯ Version
   @netlify/build 27.18.6
 ​
 ❯ Flags
   baseRelDir: true
   buildId: 63355d05d8ccec0008a84bf9
   deployId: 63355d05d8ccec0008a84bfb
 ​
 ❯ Current directory
   /opt/build/repo/my-blog
 ​
 ❯ Config file
   /opt/build/repo/my-blog/netlify.toml
 ​
 ❯ Context
   production
 ​
 ❯ Using Next.js Runtime - v4.23.2
 ​
 ────────────────────────────────────────────────────────────────
   1. @netlify/plugin-nextjs (onPreBuild event)
 ────────────────────────────────────────────────────────────────
 ​
 Next.js cache restored.
 Not running Next Runtime
 ​
 (@netlify/plugin-nextjs onPreBuild completed in 123ms)
 ​
 ────────────────────────────────────────────────────────────────
   2. Build command from Netlify app
 ────────────────────────────────────────────────────────────────
 ​
 $ npm run build
 npm WARN config tmp This setting is no longer used.  npm stores temporary files in a special
 npm WARN config location in the cache, and they are managed by
 npm WARN config     [`cacache`](http://npm.im/cacache).
 > newt-blog2-starter-nextjs@1.0.0 build
 > next build && next export
 warn  - The `target` config is deprecated and will be removed in a future version.
 See more info here https://nextjs.org/docs/messages/deprecated-target-config
 Browserslist: caniuse-lite is outdated. Please run:
   npx browserslist@latest --update-db
   Why you should do it regularly: https://github.com/browserslist/browserslist#browsers-data-updating
 info  - Checking validity of types...
 Browserslist: caniuse-lite is outdated. Please run:
   npx browserslist@latest --update-db
   Why you should do it regularly: https://github.com/browserslist/browserslist#browsers-data-updating
 info  - Creating an optimized production build...
 Browserslist: caniuse-lite is outdated. Please run:
 npx browserslist@latest --update-db
 Why you should do it regularly:
 https://github.com/browserslist/browserslist#browsers-data-updating
 info  - Compiled successfully
 info  - Collecting page data...
 info  - Generating static pages (0/30)
 info  - Generating static pages (7/30)
 info  - Generating static pages (14/30)
 info  - Generating static pages (22/30)
 info  - Generating static pages (30/30)
 info  - Finalizing page optimization...
 Page                                         Size     First Load JS
 ┌ ● / (1779 ms)                              507 B           123 kB
 ├   /_app                                    0 B            72.1 kB
 ├ λ /404                                     2.45 kB        74.5 kB
 ├ ● /archive/[slug] (1864 ms)                518 B           123 kB
 ├   └ /archive/2022 (1864 ms)
 ├ ● /archive/[slug]/page/[page] (1826 ms)    527 B           123 kB
 ├   └ /archive/2022/page/1 (1826 ms)
 ├ ● /article/[slug] (4401 ms)                4.22 kB         187 kB
 ├   ├ /article/newt-blog2 (1503 ms)
 ├   ├ /article/ ManagementPolicy1 (1474 ms)
 ├   └ /article/newt-blog1 (1424 ms)
 ├ ● /author/[slug] (1816 ms)                 518 B           123 kB
 ├   └ /author/teto (1816 ms)
 ├ ● /author/[slug]/page/[page] (1797 ms)     527 B           123 kB
 ├   └ /author/teto/page/1 (1797 ms)
 ├ ○ /Inquiry (999 ms)                        1.98 kB        90.9 kB
 ├   └ css/a22acf05b8be9443.css               1.1 kB
 ├ ○ /Licence (1208 ms)                       2.97 kB        91.9 kB
 ├ ● /page/[page] (1830 ms)                   517 B           123 kB
 ├   └ /page/1 (1830 ms)
 ├ ○ /PrivacyPolicy (1218 ms)                 4.84 kB        93.7 kB
 ├ ● /search (1396 ms)                        21.8 kB         184 kB
 ├   └ css/56d23cf654860bf0.css               1.43 kB
 ├ ● /tag/[slug] (7057 ms)                    516 B           123 kB
 ├   ├ /tag/development (1839 ms)
 ├   ├ /tag/react-nextjs (1748 ms)
 ├   ├ /tag/blog (1739 ms)
 ├   └ /tag/notes (1731 ms)
 └ ● /tag/[slug]/page/[page] (24610 ms)       524 B           123 kB
     ├ /tag/react-nextjs/page/2 (2078 ms)
     ├ /tag/react-nextjs/page/3 (2070 ms)
     ├ /tag/react-nextjs/page/5 (2069 ms)
     ├ /tag/react-nextjs/page/4 (2045 ms)
     ├ /tag/react-nextjs/page/8 (1951 ms)
     ├ /tag/react-nextjs/page/6 (1940 ms)
     ├ /tag/development/page/1 (1875 ms)
     └ [+6 more paths] (avg 1764 ms)
 + First Load JS shared by all                72.1 kB
   ├ chunks/framework-5f4595e5518b5600.js     42 kB
   ├ chunks/main-01df828e572375b9.js          27.6 kB
   ├ chunks/pages/_app-3e2d95c03c8c2a5f.js    1.53 kB
   ├ chunks/webpack-cb7634a8b6194820.js       884 B
   └ css/53017e237851091b.css                 289 B
 λ  (Lambda)  server-side renders at runtime (uses getInitialProps or getServerSideProps)
 ○  (Static)  automatically rendered as static HTML (uses no initial props)
 ●  (SSG)     automatically generated as static HTML + JSON (uses getStaticProps)
 warn  - The `target` config is deprecated and will be removed in a future version.
 See more info here https://nextjs.org/docs/messages/deprecated-target-config
 Browserslist: caniuse-lite is outdated. Please run:
   npx browserslist@latest --update-db
   Why you should do it regularly: https://github.com/browserslist/browserslist#browsers-data-updating
 info  - using build directory: /opt/build/repo/my-blog/.next
 info  - Copying "static build" directory
 info  - No "exportPathMap" found in "/opt/build/repo/my-blog/next.config.js". Generating map from "./pages"
 Error: Image Optimization using Next.js' default loader is not compatible with `next export`.  Possible solutions:
     - Use `next start` to run a server, which includes the Image Optimization API.
     - Use any provider which supports Image Optimization (like Vercel).
     - Configure a third-party loader in `next.config.js`.
     - Use the `loader` prop for `next/image`.
   Read more: https://nextjs.org/docs/messages/export-image-api
     at /opt/build/repo/my-blog/node_modules/next/dist/export/index.js:257:23
     at async Span.traceAsyncFn (/opt/build/repo/my-blog/node_modules/next/dist/trace/trace.js:75:20)
 ​
 ────────────────────────────────────────────────────────────────
   "build.command" failed
 ────────────────────────────────────────────────────────────────
 ​
   Error message
   Command failed with exit code 1: npm run build (https://ntl.fyi/exit-code-1)
 ​
   Error location
   In Build command from Netlify app:
   npm run build
 ​
   Resolved config
   build:
     base: /opt/build/repo/my-blog
     command: npm run build
     commandOrigin: ui
     environment:
       - NEXT_PUBLIC_GOOGLE_FORM_URL
       - NEXT_PUBLIC_NEWT_API_TOKEN
       - NEXT_PUBLIC_NEWT_API_TYPE
       - NEXT_PUBLIC_NEWT_APP_UID
       - NEXT_PUBLIC_NEWT_ARTICLE_MODEL_UID
       - NEXT_PUBLIC_NEWT_AUTHOR_MODEL_UID
       - NEXT_PUBLIC_NEWT_SPACE_UID
       - NEXT_PUBLIC_NEWT_TAG_MODEL_UID
       - NEXT_PUBLIC_PAGE_LIMIT
       - SITE_URL
       - NETLIFY_NEXT_PLUGIN_SKIP
     publish: /opt/build/repo/my-blog/.next
     publishOrigin: ui
   plugins:
     - inputs: {}
       origin: config
       package: '@netlify/plugin-nextjs'
 Caching artifacts
 Started saving node modules
 Finished saving node modules
 Started saving build plugins
 Finished saving build plugins
 Started saving yarn cache
 Finished saving yarn cache
 Started saving pip cache
 Finished saving pip cache
 Started saving emacs cask dependencies
 Finished saving emacs cask dependencies
 Started saving maven dependencies
 Finished saving maven dependencies
 Started saving boot dependencies
 Finished saving boot dependencies
 Started saving rust rustup cache
 Finished saving rust rustup cache
 Started saving go dependencies
 Finished saving go dependencies
 Build failed due to a user error: Build script returned non-zero exit code: 2
 Creating deploy upload records
 Failing build: Failed to build site
 Failed during stage 'building site': Build script returned non-zero exit code: 2 (https://ntl.fyi/exit-code-2)
 Finished processing build request in 46.588910191s

該当のソースコード

netlify.toml

[build]
  command = "next build" //ここ変更するとビルドエラーになってしまう。

[[plugins]]
  package = "@netlify/plugin-nextjs"

package.json

"scripts": {
	"dev": "next dev",
	"build": "next build",
	"postbuild": "next-on-netlify",
	"export": "next export",
	"postexport": "next-sitemap",
	"deploy": "npm run build && npm run export",
	"start": "next start",
	"lint": "next lint"
	}

next-sitemap.js

module.exports = {
	siteUrl: "https://teto-tech.com/",
	changefreq: "weekly",
	generateRobotsTxt: true,
	sitemapSize: 7000,
	outDir: "./out",
};