這是我寫的測試，我的問題是，我試圖盡可能健壯地構建它，但它有時會工作，有時會由于如下所示的原因而失敗。也許我遺漏了一些東西，如果你們中的任何一個能幫助我使測試更健壯，我將不勝感激。注意：我從代碼中刪除了敏感信息。const { getStatement, portalLogin, getDeletableList } = require("./helper.js");const user = { userName: "*****@*****.de", passWord: "*******" };const puppeteer = require("puppeteer");const headlessVal = false;const webSiteUrlLogin = "https://... .de/dashboard";const webSiteUrlMe = "https://... .de/me";// elements with classesconst change_username_button = ".change-username-button";const save_user_changes_btn = ".save-user-changes-btn";// elements with ID'sconst user_personal_title = "#user_personal_title";// [happy path] 1 user changes #user_personal_titletest("[happy path] 1 user changes #user_personal_title", async () => {  //////// SETUP & LOGIN  START /////////  const browser = await puppeteer.launch({    headless: headlessVal,    args: ["--window-size=1920,1080"],    defaultViewport: null,  });  // new browser window opens  const page = await browser.newPage();  // open specified url and waits for it to be loaded  await page.goto(webSiteUrlLogin, {    //wait until there are no more conections that traffic    waitUntil: "networkidle0",  });  await page.waitForNavigation({    waitUntil: "networkidle2",  });  const user_local = {    userName:      user.userName !== undefined ? user.userName : process.env.USERNAME,    passWord:      user.passWord !== undefined ? user.passWord : process.env.PASSWORD,  };失敗：Evaluation failed: TypeError: Cannot set property 'value' of null      at __puppeteer_evaluation_script__:2:55      at ExecutionContext._evaluateInternal (node_modules/puppeteer/lib/cjs/puppeteer/common/ExecutionContext.js:217:19)      at ExecutionContext.evaluate (node_modules/puppeteer/lib/cjs/puppeteer/common/ExecutionContext.js:106:16)      at Object.<anonymous> (joyce_PORTAL/end-to-end/me.test.js:168:3)