Astro+Svelte library: Module name, 'clsx' does not resolve to a valid URL - only in Prod! | Astro Lounge | Page 1

My astro.config.js file:

export default defineConfig({
  integrations: [
    svelte({
      preprocess: [sveltePreprocess({
        postcss: true,
      })]
    }),
    tailwind(),
    compress()
  ],
  output: "server",
  adapter: node({ mode: "standalone" }),
  devToolbar: { enabled: true },
  vite: {
    build: {
      ssr: true,
      ssrManifest: true,
      cssMinify: "lightningcss",
      ssrEmitAssets: true,
    },
    resolve: {
      preserveSymlinks: true,
      alias: {
        '$components': '/src/components',
        '$layouts': '/src/layouts',
        '$styles': '/src/styles',
        '$utils': '/src/utils',
        '$actions': '/src/actions',
      }
    }
  }
});

📎 message.txt

The Svelte package's package.json file:

{
  "name": "pages",
  "version": "0.0.1",
  "scripts": {
    "dev": "vite dev",
    "build": "vite build && npm run package",
    "preview": "vite preview",
    "package": "svelte-kit sync && svelte-package && publint",
    "prepublishOnly": "npm run package",
    "check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json",
    "check:watch": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json --watch",
    "lint": "eslint ."
  },
  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "svelte": "./dist/index.js"
    }
  },
  "files": [
    "dist",
    "!dist/**/*.test.*",
    "!dist/**/*.spec.*"
  ],
  "dependencies": {
    "svelte": "^4.0.0",
    "@iconify/svelte": "^3.1.6",
    "bits-ui": "^0.19.3",
    "clsx": "^2.1.0",
    "lucide-svelte": "^0.344.0",
    "tailwind-merge": "^2.2.1",
    "tailwind-variants": "^0.2.0"
  },
  "devDependencies": {
    "@cloudflare/workers-types": "^4.20240222.0",
    "@iconify/icons-fa6-brands": "^1.2.11",
    "@iconify/icons-logos": "^1.2.36",
    "@iconify/icons-material-symbols": "^1.2.58",
    "@sveltejs/adapter-auto": "^3.0.0",
    "@sveltejs/adapter-cloudflare": "^4.4.0",
    "@sveltejs/kit": "^2.0.0",
    "@sveltejs/package": "^2.0.0",
    "@sveltejs/vite-plugin-svelte": "^3.0.0",
    "@types/eslint": "^8.56.0",
    "@typescript-eslint/eslint-plugin": "^7.0.0",
    "@typescript-eslint/parser": "^7.0.0",
    "autoprefixer": "^10.4.16",
    "eslint": "^8.56.0",
    "eslint-plugin-svelte": "^2.36.0-next.4",
    "postcss": "^8.4.32",
    "postcss-load-config": "^5.0.2",
    "publint": "^0.1.9",
    "svelte-check": "^3.6.0",
    "tailwindcss": "^3.3.6",
    "tslib": "^2.4.1",
    "types": "file:../types",
    "typescript": "^5.0.0",
    "vite": "^5.0.11"
  },
  "svelte": "./dist/index.js",
  "types": "./dist/index.d.ts",
  "type": "module"
}

again in dev/local, everything is fine nothing to worry about -- only after a build and in preview (or deployment) that the error appears in the browser

#Astro+Svelte library: Module name, 'clsx' does not resolve to a valid URL - only in Prod!