GitLab执行nuxt generate报TypeError: external_defu_ is not a function

在GitLab的Docker环境（Node版本v12.16.3）中为Nuxt项目执行generate构建命令时，每个待生成页面都会抛出如下异常，导致页面生成失败：

[error]  /Dashboard
TypeError: external_defu_ is not a function
    at server.js:12669:45
    at Array.reduce (<anonymous>)
    at new runtime_BaseScheme (node_modules/@nuxtjs/auth-next/dist/runtime.mjs:883:0)
    at new runtime_Oauth2Scheme (node_modules/@nuxtjs/auth-next/dist/runtime.mjs:1137:0)
    at auth (node_modules/.cache/nuxt/auth.js:45:0)
    at createApp (node_modules/.cache/nuxt/index.js:291:0)
    at runNextTicks (node:internal/process/task_queues:61:5)
    at listOnTimeout (node:internal/timers/526:9)
    at processTimers (node:internal/timers/500:7)
    at async module.exports.__webpack_exports__.default (node_modules/.cache/nuxt/server.js:85:0)

相同Node版本下本地执行generate命令可正常完成所有页面生成，对应项目package.json配置如下：

{
"name": "xxx",
"version": "1.0.0",
"description": "xxx",
"author": "Alessandro",
"private": true,
"scripts": {
"generate": "ENV=production nuxt generate",
generate",
"lint": "eslint --ext .js,.vue --ignore-path .gitignore ."
},
"dependencies": {
"@nuxtjs/auth": "^4.9.1",
"@nuxtjs/auth-next": "5.0.0-1613647907.37b1156",
"@nuxtjs/axios": "^5.13.1",
"@nuxtjs/pwa": "^3.3.4",
"@vue/composition-api": "^0.6.7",
"aws-sdk": "^2.610.0",
"axios": "^0.21.1",
"bcryptjs": "^2.4.3",
"browser-image-compression": "^1.0.14",
"caniuse-lite": "^1.0.30001257",
"chart.js": "^2.9.3",
"child_process": "^1.0.2",
"compass": "^0.1.1",
"cookie": "^0.4.0",
"cookie-universal-nuxt": "^2.1.4",
"cors": "^2.8.5",
"cross-fetch": "^3.1.5",
"file-saver": "^2.0.2",
"fs": "0.0.1-security",
"gapi-script": "^1.2.0",
"install": "^0.13.0",
"js-cookie": "^2.2.1",
"kaleidoscopejs": "1.0.18",
"leaflet": "^1.6.0",
"lodash": "^4.17.15",
"md5": "^2.2.1",
"moment": "^2.29.3",
"multer": "^1.4.2",
"net": "^1.0.2",
"node-fetch": "^2.6.7",
"node-orientdb-http": "^0.1.1",
"npm": "^8.13.1",
"nuxt": "^2.15.0",
"nuxt-gmaps": "^1.2.10",
"nuxt-i18n": "^6.3.0",
"nuxt-leaflet": "0.0.19",
"nuxt-sass-resources-loader": "^2.0.5",
"p-iteration": "^1.1.8",
"pannellum": "github:saidmoya12/pannellum",
"panolens": "^0.12.1",
"proxy": "^1.0.2",
"readline": "^1.3.0",
"simple-analytics-vue": "^1.1.5",
"tls": "0.0.1",
"videojs": "^1.0.0",
"videojs-panorama": "^0.1.7",
"vue": "2.6.14",
"vue-chartjs": "^3.5.0",
"vue-cookie-accept-decline": "^5.3.1",
"vue-expandable-image": "^0.1.0",
"vue-google-login": "^2.0.3",
"vue-pannellum": "^0.5.3",
"vue-plausible": "^1.2.1",
"vue-rangedate-picker": "^1.0.0",
"vue-rangedate-picker-winslow": "^1.0.8",
"vue-server-renderer": "^2.6.12",
"vue-template-compiler": "^2.6.12",
"vue-tooltipster": "^1.2.0",
"vue-upload-multiple-image": "^1.1.4",
"vue2-google-maps": "^0.10.7",
"vue2-leaflet": "^2.6.0",
"vuedraggable": "^2.23.2",
"vuejs-panorama": "^1.1.9",
"vuejs-vr": "^1.2.2",
"vuetify": "^2.5.12",
"vuex-persistedstate": "^3.0.1",
"webpack": "^4.45.0"
},
"devDependencies": {
"@aceforth/nuxt-optimized-images": "^1.4.0",
"@nuxt/bridge": "npm:@nuxt/bridge-edge@^3.0.0-27268729.5b8e10f",
"@nuxt/image": "^0.7.1",
"@nuxt/types": "^2.14.12",
"@nuxtjs/dotenv": "^1.4.1",
"@nuxtjs/eslint-config": "^3.1.0",
"@nuxtjs/eslint-module": "^2.0.0",
"@nuxtjs/google-analytics": "^2.4.0",
"@nuxtjs/vuetify": "^1.12.3",
"babel-eslint": "^10.0.1",
"eslint": "^7.5.0",
"eslint-plugin-nuxt": ">=0.4.2",
"imagemin-gifsicle": "^7.0.0",
"imagemin-mozjpeg": "^9.0.0",
"imagemin-pngquant": "^9.0.2",
"imagemin-svgo": "^9.0.0",
"lqip-loader": "^2.2.1",
"responsive-loader": "^2.3.0",
"rimraf": "^3.0.2",
"sharp": "^0.30.7",
"sqip-loader": "^1.0.0",
"webp-loader": "^0.6.0"
}
}

报错核心是@nuxtjs/auth-next依赖的defu包版本不兼容：当前使用的@nuxtjs/auth-next版本以CommonJS规范引入defu，而6.x及以上版本的defu是纯ESM包，CJS方式引入时只会拿到模块对象而非默认导出函数，调用时就会抛出is not a function错误。
本地环境正常是因为本地依赖安装时拉取的是兼容版本的defu，GitLab CI环境如果没有按照锁文件安装依赖、或者缓存了异常版本的依赖，就会拉取到不兼容的高版本defu触发报错。另外当前package.json的scripts字段存在语法错误，也可能导致CI环境依赖解析异常。

按优先级依次操作即可解决：

• 保证CI和本地依赖版本完全一致：将本地生成的package-lock.json（或对应包管理器的锁文件）提交到Git仓库，CI脚本中使用npm ci代替npm install安装依赖，该命令会严格按照锁文件安装版本，不会自动升级符合semver范围的依赖。
• 手动固定defu的兼容版本：执行npm install defu@5.0.1 -S安装兼容CJS调用的defu 5.x版本，该版本同时支持ESM和CJS引入，不会触发该报错，禁止升级到6.x及以上版本。
• 修正package.json的语法错误：删除scripts字段下孤立的generate",行，修正后的scripts块如下：

"scripts": {
  "generate": "ENV=production nuxt generate",
  "lint": "eslint --ext .js,.vue --ignore-path .gitignore ."
}

• 清理CI异常缓存：如果CI配置了node_modules缓存，先清空现有缓存再重新执行构建，避免旧的不兼容defu包被复用。

内容的提问来源于stack exchange，提问作者Alessandro M.