在Playwright中获取选择器classList时遇Target closed错误，求解决

刚上手用Playwright测试React应用，试过StackOverflow和GitHub上的通用解决方案都无效。

我的测试代码如下：

import {expect, test} from "@playwright/test";

test.describe('App general functionality', () => {
    test('Theme switches normally', async ({page}) => {
        const app = await page.getByTestId('app');
        const themeSwitch = await page.getByTestId('themeSwitch');

        const classList = await app.evaluate(node => {
            console.log(node);
        });
        // const classList = await app.getAttribute('class');
    });
});

我已经安装了支持toHaveClass的expect类型扩展，且确认app元素存在（控制台能输出它的定位器和内部元素，app是应用根div的测试ID），但始终出现以下错误：

locator.evaluate: Target closed
=========================== logs ===========================
waiting for getByTestId('app')
============================================================

错误触发于这一行：

const classList = await app.evaluate // or app.getAttribute('class')

应用中对应的div代码：

<div data-test-id={'app'} className={`app ${appStore.isDarkTheme ? 'dark' : 'light'}`}>

内容的提问来源于stack exchange，提问作者Animus