On running "firebase emulators:start --only functions" this error shows

functions: Failed to load function definition from source: FirebaseError: Failed to parse build specification

const {firestore} = require("firebase-admin");
const {initializeApp} = require("firebase-admin/app");

const app= initializeApp();

const db = firestore();

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": "22"
  },
  "dependencies": {
    "@google-cloud/storage": "^7.15.0",
    "@sendgrid/mail": "^8.1.4",
    "cors": "^2.8.5",
    "docxtemplater": "^3.59.0",
    "firebase-admin": "^12.6.0",
    "firebase-functions": "^6.3.1",
    "fs-extra": "^11.3.0",
    "googleapis": "^144.0.0",
    "nodemailer": "^6.10.0",
    "pizzip": "^3.1.8",
    "stripe": "^17.6.0",
    "uuid": "^11.0.5"
  },
  "devDependencies": {
    "eslint": "^8.15.0",
    "eslint-config-google": "^0.14.0",
    "eslint-plugin-promise": "^4.0.1",
    "firebase-functions-test": "^3.1.0"
  },
  "private": true
}