Forwarding options to remarkPlugins/rehypePlugins can break them

Subject of the issue

Currently @mdx-js/mdx forwards its options to every plugin in remarkPlugins and rehypePlugins, which can easily lead to some of them breaking. Is there a specific reason why we’re doing this? If it’s a behavior left over from something else, I can remove it.

Your environment

• Name and version of operating system: macOS 10.14.4
• Names and version of required packages: 1.0.18
• Version of node, npm, yarn, or names and versions of browser: yarn 1.16.0

Steps to reproduce

import mdx from '@mdx-js/mdx'
import detectFrontmatter from 'remark-frontmatter'

const content = `
---
title: Hello World!
---
`

mdx(content, {
  remarkPlugins: [
    detectFrontmatter,
  ],
})

Expected behaviour

remark-frontmatter shouldn’t be getting unexpected options.

Actual behaviour

Options from the mdx() call get forwarded to remark-frontmatter, which thinks we’re passing the definition for detecting frontmatter, but the shape of the object doesn’t satisfy its criteria so it crashes.

Temporary workaround

Passing undefined as an option to all plugins, which results in default, i.e. expected behavior.

mdx(content, {
  remarkPlugins: [
    [detectFrontmatter, undefined],
  ],
})

[wooorm]

I suspect there is a teeny tiny extremely slim chance someone depends and we’d break something if we patch it up. If we do a major (or wait for one) the chance of someone being on ^1.0.0 and trying to use a plugin that breaks is much much much larger.

I also think @silvenon has a good enough understanding of remark and MDX that he can figure out what happened rather easily, but I don’t think many other persons using MDX can figure out what’s failing, resulting in a pretty bad debugging experience.

Therefore I propose patching this up instead of a major release. We can add a note about this in releases though.

[johno]

Released as https://github.com/mdx-js/mdx/releases/tag/v1.0.19