[Ethereum] Error HH8: There’s one or more errors in your config file, Expected a value of type HttpNetworkConfig

Why is Hardhat throwing an error? I copy n pasted the default config file from https://hardhat.org/config/?

*Error HH8: There's one or more errors in your config file:
 Invalid value {"url":"https://eth-rinkeby.alchemyapi.io/v2/xxxxxxxxxx","accounts":[null]} for HardhatConfig.networks.rinkeby - Expected a value of type HttpNetworkConfig.*

To learn more about Hardhat's configuration, please go to https://hardhat.org/config/

/**
 * @type import('hardhat/config').HardhatUserConfig
 */
require("@nomiclabs/hardhat-waffle");
require("@nomiclabs/hardhat-ethers");
require("@nomiclabs/hardhat-truffle5");
require("@nomiclabs/hardhat-etherscan");
require("hardhat-deploy");

require("dotenv").config();

const privateKey1 = process.env.PRIVATE_KEY;
const etherscanKey = process.env.ETHERSCAN_API_KEY;

module.exports = {
  defaultNetwork: "rinkeby",
  networks: {
    hardhat: {},
    rinkeby: {
      url: "https://eth-rinkeby.alchemyapi.io/v2/oL89FHmvkiWEfUgdjWON4NZBnB-497Is",
      accounts: [privateKey1],
    },
  },
  solidity: {
    version: "0.8.0",
    settings: {
      optimizer: {
        enabled: true,
        runs: 200,
      },
    },
  },
  paths: {
    sources: "./contracts",
    tests: "./test",
    cache: "./cache",
    artifacts: "./artifacts",
  },
  mocha: {
    timeout: 20000,
  },
};