Comments may no longer appear before frontmatter

[remcohaszing]

Description

In mermaid 10.9.1 it’s allowed to add a comment before the frontmatter. In mermaid 11, it’s not.

Steps to reproduce

Paste the diagram below into the mermaid live editor

Screenshots

From the browser console in the live editor:

Code Sample

%%{
  init: {
    "fontFamily": "arial,sans-serif"
  }
}%%
---
title: Node
---
flowchart LR
    id

Setup

• Mermaid version: v11.2.1
• Browser and Version: Chrome 129.0.6668.70

Suggested Solutions

Either document this as a breaking change, or add back support.

Additional Context

I’m running into this in mermaid-isomorphic because of this test and this test fixture.