Describe the bug

For yaml file

# yaml-language-server: $schema=https://aka.ms/teams-toolkit/v1.7/yaml.schema.json
# Visit https://aka.ms/teamsfx-v5.0-guide for details on this file
# Visit https://aka.ms/teamsfx-actions for details on actions
version: v1.7

Use below js to parse it:

const yaml = require("yaml")
const fs = require("fs");
const yamlContent = fs.readFileSync("example.yaml", "utf8");
const parsedYaml = yaml.parseDocument(yamlContent);
console.log(parsedYaml.commentBefore);

And the commentBefore is null

To Reproduce
Just as above

Expected behaviour
commentBefore should not be null

Versions (please complete the following information):

• Environment: 18
• yaml: 2.7.0.

Additional context
No