Unable to get User Information

# Unable to get user information

## Code used to reproduce
```js
import { LeetCode } from "leetcode-query";

const leetcode = new LeetCode();
const user = await leetcode.user("username");
```

## Error

```bash
Uncaught (in promise) TypeError: Failed to execute 'fetch' on 'Window': Illegal invocation
at _fetch (index.js:71:1)
at get_csrf (index.js:87:1)
at Credential.init (index.js:111:1)
at getUser (Card.js:10:1)
at Card (Card.js:15:1)
at renderWithHooks (react-dom.development.js:15486:1)
at mountIndeterminateComponent (react-dom.development.js:20103:1)
at beginWork (react-dom.development.js:21626:1)
at beginWork$1 (react-dom.development.js:27465:1)
at performUnitOfWork (react-dom.development.js:26596:1)
```

Help me with this. @JacobLinCool

该故障通过 index.js 中的 _fetch、get_csrf 和 Credential.init 报告，其中 Card.js 调用 getUser。复现 issue 中所示的浏览器调用，并跟踪 fetch 的调用；当 leetcode.user("username") 返回用户信息且不再出现 Illegal invocation 错误时，即表示完成。

由索引模型根据 Issue 内容生成。