fix: add mermaid-mindmap support

Adds and tests basic support for mermaid-mindmaps.

Issues
======

- mermaid-mindmap is currently loaded from a CDN, which isn't good.
  This means that mindmaps won't work if there is no internet
  connection (or if the network blocks CDNs).
- mermaid won't load mermaid-mindmap using mermaid.initThrowsErrors
  until PR mermaid-js/mermaid#3702
  is merged and released

src/index.js

@@ -197,19 +197,25 @@ async function renderMermaid (browser, definition, outputFormat, { viewport, bac
     await page.$eval('body', (body, backgroundColor) => {
       body.style.background = backgroundColor
     }, backgroundColor)
-    const metadata = await page.$eval('#container', (container, definition, mermaidConfig, myCSS, backgroundColor) => {
+    const metadata = await page.$eval('#container', async (container, definition, mermaidConfig, myCSS, backgroundColor) => {
       container.textContent = definition
-      window.mermaid.initialize(mermaidConfig)
+      await window.mermaid.initialize({
+        lazyLoadedDiagrams: [
+          // TODO: bundle mermaid-mindmap instead of downloading from CDN
+          'https://cdn.jsdelivr.net/npm/@mermaid-js/mermaid-mindmap@9.2.0-rc5/dist/mermaid-mindmap-detector.esm.mjs'
+        ],
+        ...mermaidConfig
+      })
       // should throw an error if mmd diagram is invalid
       try {
-        window.mermaid.initThrowsErrors(undefined, container)
+        await window.mermaid.initThrowsErrors(undefined, container)
       } catch (error) {
         if (error instanceof Error) {
           // mermaid-js doesn't currently throws JS Errors, but let's leave this
           // here in case it does in the future
           throw error
         } else {
-          throw new Error(error?.message ?? 'Unknown mermaid render error')
+          throw new Error(error?.message ?? `Unknown mermaid render error`)
         }
       }
 

test-positive/mind-map.mmd

@@ -0,0 +1,14 @@
+mindmap
+  root
+    child1((Circle))
+        grandchild 1
+        grandchild 2
+    child2(Round rectangle)
+        grandchild 3
+        grandchild 4
+    child3[Square]
+        grandchild 5
+        ::icon(mdi mdi-fire)
+        gc6((grand<br/>child 6))
+        ::icon(mdi mdi-fire)
+          gc7((grand<br/>grand<br/>child 8))