markdown-it plugins running twice?

[gureckis]

Describe the bug
It seems that markdown-it plugins are being run more than once to the same slide. For instance, I tried using the markdown-it-footnote plugin. It works ok but inserts the footnote material twice at the bottom of the slide. I reported a similar behavior in #1579 which i attributed to the editor but might also be the same issue?

To Reproduce
Steps to reproduce the behavior:

1. install markdown-it-footnote
2. add it to your vite-config.mjs:

import { defineConfig } from 'vite'
import footnote from 'markdown-it-footnote'

export default defineConfig({
  slidev: {
    vue: {
      /* vue options */
    },
    markdown: {
      /* markdown-it options */
      markdownItSetup(md) {
        /* custom markdown-it plugins */
        md.use(footnote)
      },
    },
    /* options for other plugins */
  },
})

4. made a slide with a footnote

---
layout: default
---

# Hello

- Here is a bullet^[here is a foonote]

5. Results

Desktop (please complete the following information):

• OS:
• Browser:
• Slidev version: v0.49.0-beta.6
• Markdown-it-footnote version: 4.0.0

[antfu]

Wait... probably because we have markdown-it-footnote already builtin?

[gureckis]

doh 😳!! yes confirmed, that was the issue.