Frontmatter yaml is converted to ***

[coderaiser]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Affected package

latest

Steps to reproduce

Github issues templates uses yaml, and when I lint with remark the resulting markdown is being corrupted.

import remarkFrontmatter from 'remark-frontmatter'
import remarkParse from 'remark-parse'
import remarkStringify from 'remark-stringify'
import {unified} from 'unified'

const md = `
---
layout: "solar-system"
---

# Jupiter
`;

const file = await unified()
  .use(remarkParse)
  .use(remarkStringify)
  .use(remarkFrontmatter, ['yaml'])
  .use(function () {
    return function (tree) {
      console.dir(tree)
    }
  })
  .process(md)

console.log(String(file))

Actual behavior

***

## layout: "solar-system"

# Jupiter

Expected behavior

---
layout: "solar-system"
---

# Jupiter

Runtime

No response

Package manager

No response

Operating system

No response

Build and bundle tools

No response

[ChristianMurphy]

Welcome @coderaiser 👋
Frontmatter starts on the first line of a file, you have it on the second so it isn't recognized.
Try

const markdown = `---
layout: "solar-system"
---

# Jupiter
`;

Runnable example: https://stackblitz.com/edit/github-uw6tjlky?file=src%2Fmain.ts