process.env.jwtSecret throws error in ts code example

Example 1: .env typescript

npm install dotenv;
 OR 
yarn add dotenv;


import * as dotenv from 'dotenv';

//inside your starter code, do this
...
...
dotenv.config();
...

Example 2: typescript declare process.env

declare namespace NodeJS {  export interface ProcessEnv {    HOST: string;    DB_URL: string;    DB_NAME?: string;  }}