support conditionals in sublanding FM props

Author: sarahs

lib/page.js

@@ -202,16 +202,21 @@ class Page {
 
     if (this.learningTracks) {
       const learningTracks = []
-      for await (const trackName of this.rawLearningTracks) {
-        const track = context.site.data['learning-tracks'][context.currentProduct][trackName]
+      for await (const rawTrackName of this.rawLearningTracks) {
+        // Track names in frontmatter may include Liquid conditionals
+        const renderedTrackName = await renderContent(rawTrackName, context, { textOnly: true, encodeEntities: true })
+        if (!renderedTrackName) continue
+
+        const track = context.site.data['learning-tracks'][context.currentProduct][renderedTrackName]
         if (!track) continue
         learningTracks.push({
-          trackName,
+          trackName: renderedTrackName,
           title: await renderContent(track.title, context, { textOnly: true, encodeEntities: true }),
           description: await renderContent(track.description, context, { textOnly: true, encodeEntities: true }),
           guides: await getLinkData(track.guides, context)
         })
       }
+
       this.learningTracks = learningTracks
     }