[SOLVED] Function cannot get custom variable

const sdk = require("node-appwrite");

/*
  'req' variable has:
    'headers' - object with request headers
    'payload' - request body data as a string
    'variables' - object with function variables

  'res' variable has:
    'send(text, status)' - function to return text response. Status code defaults to 200
    'json(obj, status)' - function to return JSON response. Status code defaults to 200

  If an error is thrown, a response with code 500 will be returned.
*/

module.exports = async function (req, res) {
  const client = new sdk.Client();

  // You can remove services you don't use
  const account = new sdk.Account(client);
  const avatars = new sdk.Avatars(client);
  const database = new sdk.Databases(client);
  const functions = new sdk.Functions(client);
  const health = new sdk.Health(client);
  const locale = new sdk.Locale(client);
  const storage = new sdk.Storage(client);
  const teams = new sdk.Teams(client);
  const users = new sdk.Users(client);
  const userId = req.variables["APPWRITE_FUNCTION_USER_ID"];
  //get provided token
  const token = req.variables["APPWRITE_FUNCTION_DATA"]["token"];

  if (
    !req.variables["APPWRITE_FUNCTION_ENDPOINT"] ||
    !req.variables["APPWRITE_FUNCTION_API_KEY"]
  ) {
    console.warn(
      "Environment variables are not set. Function cannot use Appwrite SDK."
    );
  } else {
    client
      .setEndpoint(req.variables["APPWRITE_FUNCTION_ENDPOINT"])
      .setProject(req.variables["APPWRITE_FUNCTION_PROJECT_ID"])
      .setKey(req.variables["APPWRITE_FUNCTION_API_KEY"])
      .setSelfSigned(true);
  }
  var user = await users.get(userId).catch((err) => {
    return err;
  });
  //check if user already has a document in the database predictor-db in colllection users
  var userDoc = await database
    .listDocuments(`predictor-db`, `users`, [], 1, 0, userId)
    .catch((err) => {
      return err;
    });
  // if not create a new one
  if (userDoc.documents.length == 0) {
    //create a new document in the database predictor-db in colllection users and set the token
    await database.createDocument(`predictor-db`, `users`, userId, {
      token: token,
    });
  } else {
    //update the token
    await database.updateDocument(
      `predictor-db`,
      `users`,
      userDoc.documents[0].$id,
      {
        token: token,
      }
    );
  }

  res.json({
    user: user,
  });
};

Error: The document payload is missing.
    at Client.call (/usr/code-start/node_modules/node-appwrite/lib/client.js:171:31)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async Databases.createDocument (/usr/code-start/node_modules/node-appwrite/lib/services/databases.js:1055:16)
    at async module.exports (/usr/code-start/src/index.js:59:5)
    at async /usr/local/src/server.js:68:13```

const token = JSON.parse(req.variables["APPWRITE_FUNCTION_DATA"] ?? '{}')["token"] ?? '';