Firebase Cloud Functions Deploy Error- SyntaxError: Unexpected token '?' - node.js

Question

I just updated to:
npm: 8.11.0
node: v16.15.1
New Edit:
I just updated again sudo n latest:
npm: 8.12.1
node: v18.4.0
I'm trying to deploy a new cloud function firebase deploy --only functions:deleteUser
but I keep getting a cli error:
Function failed on loading user code. This is likely due to a bug in
the user code. Error message: Error: please examine your function logs
to see the error cause
When I look at the log:
deleteUser
Detailed stack trace: /workspace/node_modules/firebase-admin/lib/app/firebase-namespace.js:84
this.INTERNAL = new FirebaseNamespaceInternals(appStore ?? new lifecycle_1.AppStore());
Provided module can't be loaded.
Is there a syntax error in your code?
SyntaxError: Unexpected token '?'
at wrapSafe (internal/modules/cjs/loader.js:915:16)
at Module._compile (internal/modules/cjs/loader.js:963:27)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1027:10)
at Module.load (internal/modules/cjs/loader.js:863:32)
at Function.Module._load (internal/modules/cjs/loader.js:708:14)
at Module.require (internal/modules/cjs/loader.js:887:19)
at require (internal/modules/cjs/helpers.js:74:18)
at Object.<anonymous> (/workspace/node_modules/firebase-admin/lib/default-namespace.js:19:30)
at Module._compile (internal/modules/cjs/loader.js:999:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1027:10)
Could not load the function, shutting down.
Index.js:
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
exports.deleteUser = functions.https.onCall((data, context) => {
const userID = data.userID;
admin.auth().deleteUser(userID)
.then(() => {
console.log('Successfully deleted userID: ', userID);
return true // without this Return I get a different error: Each then() should return a value or throw promise/always-return
})
.catch((error) => {
console.log('Error deleting user: ', error);
});
});
New Edit Again
Package.json:
{
"name": "functions",
"description": "Cloud Functions for Firebase",
"scripts": {
"lint": "eslint .",
"serve": "firebase emulators:start --only functions",
"shell": "firebase functions:shell",
"start": "npm run shell",
"deploy": "firebase deploy --only functions",
"logs": "firebase functions:log"
},
"engines": {
"node": "12"
},
"main": "index.js",
"dependencies": {
"#google-cloud/logging": "^8.1.1",
"firebase-admin": "^11.0.0",
"firebase-functions": "^3.11.0",
"save": "^2.4.0"
},
"devDependencies": {
"eslint": "^5.12.0",
"eslint-plugin-promise": "^4.0.1",
"firebase-functions-test": "^0.2.0"
},
"private": true
}

Answer 1

Thanks to the tip by #raina77ow in the comments. I had to go inside my package.json file and simply change the node version from 12 to 16
old:
"engines": {
"node": "12" // causes error
}
new:
"engines": {
"node": "16" // error is now gone
}

Answer 2

For users in node 12.x version:
npm install --save firebase-admin#10.3

Answer 3

The suggested solutions didn't work for me because I already use node version 16. What worked for me was replacing the firebase toolset with the latest version. I was surprised but it cleared the error. You can do that using the following command:
sudo npm install -g firebase-tools#latest --force
Now be aware that --force shouldn't be used unless you want to really replace the existing toolset (In general some should be careful with that command). Sudo was necessary in my case to execute the command with elevated rights. After that firebase deployment should work.