Unable to add mermaid remark plugin

[bennypowers]

Using this config:

import { rocketLaunch } from '@d4kmor/launch';

import remarkMermaid from 'remark-mermaid';

console.log(remarkMermaid); // [Function: mermaid]

export default {
  themes: [rocketLaunch()],
  setupUnifiedPlugins: [
    function addMermaid(plugins) {
      if (plugins.findIndex(plugin => plugin.name === 'remark-mermaid') === -1) {
        const insertAfterIndex =
          plugins.findIndex(plugin => plugin.name === 'remark2rehype');
          // plugins.findIndex(plugin => plugin.name === 'markdown'); // also doesn't work
        plugins.splice(insertAfterIndex + 1, 0, {
          name: 'remark-mermaid',
          plugin: remarkMermaid,
        });
      }
      return plugins;
    },
  ],
};

I got this error:

Problem writing Eleventy templates: (more in DEBUG output)
> Having trouble rendering liquid (and markdown) template ./docs/guides/using apollo/local-state/advanced-local-state.md

`TemplateContentRenderError` was thrown
> Unknown language: `mermaid` is not registered

stack trace

`Error` was thrown:
    Error: Unknown language: `mermaid` is not registered
        at Refractor.highlight (/Users/bennyp/Documents/apollo-elements/node_modules/refractor/core.js:115:13)
        at visitor (/Users/bennyp/Documents/apollo-elements/node_modules/rehype-prism-template/index.js:30:26)
        at overload (/Users/bennyp/Documents/apollo-elements/node_modules/unist-util-visit/index.js:27:12)
        at one (/Users/bennyp/Documents/apollo-elements/node_modules/unist-util-visit-parents/index.js:34:25)
        at all (/Users/bennyp/Documents/apollo-elements/node_modules/unist-util-visit-parents/index.js:57:16)
        at one (/Users/bennyp/Documents/apollo-elements/node_modules/unist-util-visit-parents/index.js:42:28)
        at all (/Users/bennyp/Documents/apollo-elements/node_modules/unist-util-visit-parents/index.js:57:16)
        at one (/Users/bennyp/Documents/apollo-elements/node_modules/unist-util-visit-parents/index.js:42:28)
        at visitParents (/Users/bennyp/Documents/apollo-elements/node_modules/unist-util-visit-parents/index.js:26:3)
        at visit (/Users/bennyp/Documents/apollo-elements/node_modules/unist-util-visit/index.js:22:3)
Using pathPrefix: /_site-dev
Copied 30 files / Wrote 0 files in 7.10 seconds (v0.11.1)

I'm not sure if this is something special about mermaid, if the underlying setupUnifiedPlugins needs a patch, or if I'm doing it wrong

[daKmoR]

do you have an example of the markdown using the mermaid code block?

[bennypowers]

https://github.com/apollo-elements/apollo-elements/blob/master/pages/advanced-local-state.md

<meta name="description" content="Some advanced recipes for Apollo Elements to manage local state"/>

blah blah blah

This mutation requires an input which is a list of site IDs. In order to provide that list, our user will click on the checkboxes in the list of `<select-item>`s. This in turn will write to that `Site`'s client-side `selected @client` field on `Site`, which in turn will be read to determine whether a site's corresponding `<select-item>` component will be marked selected: Whenever the user clicks on an item in the list, `onSelectItem` writes the new selected state to the cache for that Site.

```mermaid
sequenceDiagram
    participant CA as Apollo Cache
    participant UI as <all-sites>
    participant OL as <select-item>
    CA->>UI: AllSitesQuery
    UI-->>OL: Property Assignment
    OL->>UI: MouseEvent
    UI-->>CA: writeFragment
```

Then, when the user is ready to create the Network, she clicks the `Create` button, and the component issues the mutation over the network with variables based on the currently selected sites.

blah blah blah