Cannot read properties of undefined (reading 'cacheTag')

[FilipRybinski]

For which library do you need help?

native-federation

Question

Any advice on how to resolve this issue? It appears when I try to start the Node server (server.mjs).
package.json
{
"name": "microfrontends",
"version": "0.0.0",
"scripts": {
"ng": "ng",
"start": "ng serve",
"build": "ng build",
"watch": "ng build --watch --configuration development",
"test": "ng test",
"serve:ssr:host": "node dist/host/server/server.mjs"
},
"private": true,
"dependencies": {
"@angular/animations": "^19.0.0",
"@angular/common": "^19.0.0",
"@angular/compiler": "^19.0.0",
"@angular/core": "^19.0.0",
"@angular/forms": "^19.0.0",
"@angular/platform-browser": "^19.0.0",
"@angular/platform-browser-dynamic": "^19.0.0",
"@angular/platform-server": "^19.0.0",
"@angular/router": "^19.0.0",
"@angular/ssr": "^19.1.7",
"@softarc/native-federation-node": "^2.0.10",
"cors": "^2.8.5",
"es-module-shims": "^1.5.12",
"express": "^4.18.2",
"rxjs": "~7.8.0",
"tslib": "^2.3.0",
"zone.js": "~0.15.0"
},
"devDependencies": {
"@angular-architects/native-federation": "^18.2.3",
"@angular-devkit/build-angular": "^19.1.7",
"@angular/cli": "^19.0.4",
"@angular/compiler-cli": "^19.0.0",
"@types/express": "^4.17.17",
"@types/jasmine": "~5.1.0",
"@types/node": "^18.18.0",
"jasmine-core": "~5.4.0",
"karma": "~6.4.0",
"karma-chrome-launcher": "~3.2.0",
"karma-coverage": "~2.2.0",
"karma-jasmine": "~5.1.0",
"karma-jasmine-html-reporter": "~2.1.0",
"typescript": "~5.6.2"
}
}

[manfredsteyer]

Oh, this looks like a bug. I will take care of it asap.

[FilipRybinski]

Awesome, I'm waiting for updates because I was struggling with the SSR configuration. Thanks :)

[cristiannores]

I encountered the same issue with the server.mjs file generated during the build process of an Angular application utilizing Native Federation. Specifically, the problematic line:

e?.cacheTag ? `?t=${e.cacheTag}` : ""

resulted in a runtime error because e was undefined. To resolve this, I created a postbuild.js script that modifies the generated server.mjs file after the build process. Here's the content of postbuild.js:

const fs = require('fs');
const path = require('path');

const serverFilePath = path.join(__dirname, 'dist', 'mc-auth-app', 'server', 'server.mjs');

fs.readFile(serverFilePath, 'utf8', (err, data) => {
  if (err) {
    console.error('Error reading server.mjs:', err);
    return;
  }

  // Replace the problematic line
  const result = data.replace(/e\?\.(cacheTag\s?\?\s?`[^`]+`\s?:\s?"";?)/g, '(e && e.cacheTag ? `?t=${e.cacheTag}` : "")');

  fs.writeFile(serverFilePath, result, 'utf8', (err) => {
    if (err) console.error('Error writing server.mjs:', err);
    else console.log('server.mjs modified successfully.');
  });
});

In this script, replace 'mc-auth-app' with the actual name of your application.

Additionally, I observed that to run the server correctly, it was necessary to navigate to the dist/mc-auth-app/server directory and execute node server.mjs from there, due to the relative path ../browser used within the server code.

To automate these adjustments and streamline the build and serve process, I incorporated the following scripts into my package.json:

{
  "scripts": {
    "build": "ng build && node postbuild.js",
    "start:ssr": "cd dist/mc-auth-app/server && node server.mjs",
    "build-and-start": "npm run build && npm run start:ssr"
  }
}

Here's a brief overview of each script:

build: Executes the Angular build process (ng build) and then runs the postbuild.js script to apply necessary modifications to the generated server.mjs file.

start:ssr: Changes the working directory to dist/mc-auth-app/server and starts the server using node server.mjs.

build-and-start: Combines the build and serve steps by running the build script followed by the start:ssr script.

Implementing these scripts has streamlined my development workflow and resolved the issues encountered with the generated server.mjs file.

Please note that this is a temporary workaround for a known issue in the implementation. A permanent fix should be applied once the underlying bug is resolved.