postman_fetch_access_token.js

const getAccessTokenRequest = {
  url: 'http://localhost:5050',
  method: 'GET',
};

pm.sendRequest(getAccessTokenRequest, (err, res) => {
  console.log(err ? err : res.json());
  if (err === null) {
    console.log("Saving the access token");
    var responseJson = res.json();
    pm.environment.set("currentAccessToken", responseJson.access_token);
  }
});