Clearer error message from learning tracks (#32538)

Author: heiskr

lib/process-learning-tracks.js

@@ -11,6 +11,10 @@ export default async function processLearningTracks(rawLearningTracks, context)
 
   let featuredTrack
 
+  if (!context.currentProduct) {
+    throw new Error(`Missing context.currentProduct value.`)
+  }
+
   for (const rawTrackName of rawLearningTracks) {
     let isFeaturedTrack = false
 
@@ -19,9 +23,13 @@ export default async function processLearningTracks(rawLearningTracks, context)
     if (!renderedTrackName) continue
 
     // Find the data for the current product and track name.
-    const track = context.site.data['learning-tracks'][context.currentProduct][renderedTrackName]
+    const trackDataForProduct = context.site.data['learning-tracks'][context.currentProduct]
+    if (!trackDataForProduct) {
+      throw new Error(`No learning track data for product "${context.currentProduct}".`)
+    }
+    const track = trackDataForProduct[renderedTrackName]
     if (!track) {
-      throw new Error(`no learning track called '${renderedTrackName}'.`)
+      throw new Error(`No learning track called '${renderedTrackName}'.`)
     }
 
     // If there is no `versions` prop in the learning track frontmatter, assume the track should display in all versions.