Treat html-type XBlocks as units (#104)

Fixes bug where courses with html-type XBlocks as children
of sequences would ignore those children instead of treating them
as units. This caused the app to later just give up and redirect
to the course home in the old experience.

Also, handle that scenario where we have sections/sequences
with children of unexpected block types more gracefully by
logging an error instead of crashing.

TNL-7305

src/courseware/data/api.js

@@ -34,6 +34,7 @@ export function normalizeBlocks(courseId, blocks) {
           unitIds: block.children || [],
         };
         break;
+      case 'html':
       case 'vertical':
         models.units[block.id] = {
           graded: block.graded,
@@ -43,7 +44,7 @@ export function normalizeBlocks(courseId, blocks) {
         };
         break;
       default:
-        logError(`Unexpected course block type: ${block.type} with ID ${block.id}.  Expected block types are course, chapter, sequential, and vertical.`);
+        logError(`Unexpected course block type: ${block.type} with ID ${block.id}.  Expected block types are course, chapter, sequential, vertical, and html.`);
     }
   });
 
@@ -61,7 +62,11 @@ export function normalizeBlocks(courseId, blocks) {
   Object.values(models.sections).forEach(section => {
     if (Array.isArray(section.sequenceIds)) {
       section.sequenceIds.forEach(sequenceId => {
-        models.sequences[sequenceId].sectionId = section.id;
+        if (sequenceId in models.sequences) {
+          models.sequences[sequenceId].sectionId = section.id;
+        } else {
+          logError(`Section ${section.id} has child block ${sequenceId}, but that block is not in the list of sequences.`);
+        }
       });
     }
   });
@@ -69,7 +74,11 @@ export function normalizeBlocks(courseId, blocks) {
   Object.values(models.sequences).forEach(sequence => {
     if (Array.isArray(sequence.unitIds)) {
       sequence.unitIds.forEach(unitId => {
-        models.units[unitId].sequenceId = sequence.id;
+        if (unitId in models.units) {
+          models.units[unitId].sequenceId = sequence.id;
+        } else {
+          logError(`Sequence ${sequence.id} has child block ${unitId}, but that block is not in the list of units.`);
+        }
       });
     }
   });