Google login in thunkable project

[tony.ycy.program]

let ss = SpreadsheetApp.getActiveSpreadsheet();
const commandError = {
  "error": true,
  "errorMessage": "The command is invalid."
}

function doPost(e) {
  let sheet = ss.getSheetByName("user");
  let userToken = e.parameter.token;
  let getId = e.parameter.getid;
  let url = "https://oauth2.googleapis.com/tokeninfo?id_token=" + userToken;
  let response = JSON.parse(UrlFetchApp.fetch(url).getContentText());
  if (response.error != "invalid_token") {
    let googleId = response.sub;
    let email = response.email;
    let name = response.name;
    let picture = response.picture;

    let lastRow = sheet.getLastRow();
    let sheetData = sheet.getRange(2, 1, lastRow - 1, 1).getValues();
    for (let i = 0; i < lastRow - 1; i++) {
      if (sheetData[i][0] == getId) {
        sheet.getRange(i + 2, 2).setValue(googleId);
        sheet.getRange(i + 2, 3).setValue(email);
        sheet.getRange(i + 2, 4).setValue(name);
        sheet.getRange(i + 2, 5).setValue(picture);
      }
    }

    let returnValue = {
      "login": true,
      "id": googleId,
      "email": email,
      "name": name
    }
    console.log(returnValue);
    return ContentService.createTextOutput(JSON.stringify(returnValue)).setMimeType(ContentService.MimeType.JSON);
  }
}

function doGet(e) {
  let sheet = ss.getSheetByName("user");
  let command = e.parameter.command;
  let getId = "";
  let lastRow = sheet.getLastRow();
  let returnValue = {};
  switch (command) {
    case "newLogin":
      getId = makeGetid();
      sheet.getRange(lastRow + 1, 1).setValue(getId);
      returnValue = {
        "error": false,
        "getId": getId
      }
      return ContentService.createTextOutput(JSON.stringify(returnValue)).setMimeType(ContentService.MimeType.JSON);
      break;
    case "checkLogin":
      getId = e.parameter.getid;
      let sheetData = sheet.getRange(2, 1, lastRow - 1, 5).getValues();
      for (let i = 0; i < lastRow - 1; i++) {
        if (sheetData[i][0] == getId) {
          if (!(sheetData[i][1] == "" || sheetData[i][2] == "" || sheetData[i][3] == "" || sheetData[i][4] == "")) {
            returnValue = {
              "error": false,
              "googleId": sheetData[i][1],
              "email": sheetData[i][2],
              "name": sheetData[i][3],
              "picture": sheetData[i][4]
            };
            sheet.deleteRow(i + 2);
          } else {
            returnValue = {
              "error": true,
              "errorMessage": "User is not logged in."
            };
          }
        }
      }
      if (returnValue.error == undefined) {
        returnValue = {
          "error": true,
          "errorMessage": " The getId is invalid."
        };
      }
      return ContentService.createTextOutput(JSON.stringify(returnValue)).setMimeType(ContentService.MimeType.JSON);
      break;
    default:
      return ContentService.createTextOutput(JSON.stringify(commandError)).setMimeType(ContentService.MimeType.JSON);


  }
}
function makeGetid() {
  let aToz = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"];
  let getId = "";
  for (let i = 0; i < 30; i++) {
    getId = getId + aToz[random(0, 25)];
  }
  getId = getId + Date.now();
  console.log(getId);
  return getId;
}

function random(mn, mx) {
  return Math.floor(Math.random() * (mx - mn)) + mn;
}