I was trying to deploy my first typescript app on heroku. But, I ended up with 2 error first the h=10 code error which I looked up all over the internet and tried all the fixes but the error still persists. the Other error is “Cannot find package ‘express’ imported from /app/backend/dist/server.js
” I have checked node modules the app is wroking fine locally but not when I deploy it to heroku.

This is package.json

{
  "name": "podcast",
  "version": "1.0.0",
  "description": "A podcast streaming platform",
  "main": "dist/server.js",
  "type": "module",
  "scripts": {
    "start": "node dist/server.js",
    "build": "tsc",
    "dev": "tsx watch src/server.ts"
  },
  "author": "Rakshit Gumber",
  "license": "ISC",
  "dependencies": {
    "aedos": "^1.1.4",
    "bcryptjs": "^2.4.3",
    "cors": "^2.8.5",
    "dotenv": "^16.4.5",
    "express": "^4.19.2",
    "jsonwebtoken": "^9.0.2",
    "mongoose": "^8.4.5",
    "nodemailer": "^6.9.14"
  },
  "devDependencies": {
    "@types/bcryptjs": "^2.4.6",
    "@types/cors": "^2.8.17",
    "@types/express": "^4.17.21",
    "@types/jsonwebtoken": "^9.0.6",
    "@types/node": "^20.14.10",
    "@types/nodemailer": "^6.4.15",
    "nodemon": "^3.1.4",
    "ts-node": "^10.9.2",
    "ts-node-dev": "^2.0.0",
    "tsx": "^3.8.0",
    "typescript": "^5.5.3"
  }
}

tsconfig(i thaught it would be necessary):

{
  "compilerOptions": {
    "target": "ESNext",
    "module": "ESNext",
    "moduleResolution": "node",
    "jsx": "react-jsx",
    "allowJs": true,
    "outDir": "./dist",
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "skipLibCheck": true,
    "types": ["node"],
    "resolveJsonModule": true,
    "isolatedModules": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "noEmit": true,
    "allowImportingTsExtensions": true
  },
  "include": ["src/**/*.ts", "src/**/*.tsx"],
  "exclude": ["node_modules", "dist", "client"]
}

Procfile:
web:npm --prefix backend start

the folder structure is like

/project-root
backend
src
dist
package.json
tsconfig.json
│ └── …
frontend
src
public
package.json
│ └── …
├── .gitignore
Procfile
README.md
package.json

also this is package.json of root directory:

{
  "name": "podcast-project",
  "version": "1.0.0",
  "description": "A podcast streaming platform with backend and frontend in one repository",
  "scripts": {
    "start": "npm --prefix backend start"
  },
  "dependencies": {},
  "devDependencies": {},
  "engines": {
    "node": "20.10.0"
  }
}

I have tried all the trouble shooting written over the internet but error still persists. I tried restarting heroku app. And i tried deleting all the modules and dowloading them again