Drill 29: Explain each line — Environment and config

import 'dotenv/config'

function required(name: string): string {
  const value = process.env[name]
  if (!value) {
    throw new Error('Missing required environment variable: ' + name)
  }
  return value
}

export const config = {
  port: Number(process.env.PORT ?? 3000),
  databaseUrl: required('DATABASE_URL'),
  logLevel: process.env.LOG_LEVEL ?? 'info',
}

export function redactedConfig() {
  const { databaseUrl, ...rest } = config
  return rest
}

console.log(redactedConfig())