The `git-opfs` demo throw a `TypeError` when use the `git.statusMatrix` method

[fengyuanchen]

1. Start the git-opfs demo.
2. Append the following code after line 35 of the main.ts:

const statusMatrix = await git.statusMatrix({
  fs,
  dir: '/repo',
});
console.log('statusMatrix', statusMatrix);

3. Open https://localhost:9876/.
4. You will see the error in the console:

TypeError: Failed to execute 'getFileHandle' on 'FileSystemDirectoryHandle': Name is not allowed.

Related issue in isomorphic-git: isomorphic-git/isomorphic-git#1839