WARNING: Module "DHT22" not found

You can embed the module in your code like this (and there is no need for require anymore):

function DHT22(pin) {
  this.pin = pin;
}

DHT22.prototype.read = function (cb, n) {
  if (!n) n = 10;
  var d = '';
  var ht = this;
  digitalWrite(ht.pin, 0);
  pinMode(ht.pin, 'output');
  this.watch = setWatch(
    function (t) {
      d += 0 | (t.time - t.lastTime > 0.00005);
    },
    ht.pin,
    { edge: 'falling', repeat: true }
  );
  setTimeout(function () {
    pinMode(ht.pin, 'input_pullup');
    pinMode(ht.pin);
  }, 1);
  setTimeout(function () {
    if (ht.watch) {
      ht.watch = clearWatch(ht.watch);
    }
    var cks =
      parseInt(d.substr(2, 8), 2) +
      parseInt(d.substr(10, 8), 2) +
      parseInt(d.substr(18, 8), 2) +
      parseInt(d.substr(26, 8), 2);
    if (cks && (cks & 0xff) == parseInt(d.substr(34, 8), 2)) {
      cb({
        raw: d,
        rh: parseInt(d.substr(2, 16), 2) * 0.1,
        temp: parseInt(d.substr(19, 15), 2) * 0.2 * (0.5 - d[18]),
      });
    } else {
      if (n > 1)
        setTimeout(function () {
          ht.read(cb, --n);
        }, 500);
      else cb({ err: true, checksumError: cks > 0, raw: d, temp: -1, rh: -1 });
    }
  }, 50);
};

const dht22 = new DHT22(NodeMCU.D5);

const readDHT22Sensor = () => {
  digitalWrite(D2, false);
  dht22.read(e => {
    console.log(
      '[DHT22 sensor]  ' +
        new Date().toString() +
        ' temperature: ' +
        e.temp.toString() +
        '°C, humidity: ' +
        e.rh.toString() +
        '%'
    );
    digitalWrite(D2, true);
  });
};

readDHT22Sensor();
setInterval(() => readDHT22Sensor(), 1000);