add sort method and test

lib/response_massager.js

@@ -1,7 +1,7 @@
 const LocationLabelUpdater = require('./location_label_updater')
 const AvailabilityResolver = require('./availability_resolver.js')
 const parallelFieldsExtractor = require('./parallel-fields-extractor')
-const { isAeonUrl } = require('../lib/util')
+const { isAeonUrl, sortOnPropWithUndefinedLast } = require('../lib/util')
 const FulfillmentResolver = require('./fulfillment_resolver')
 const RequestabilityResolver = require('./requestability_resolver')
 
@@ -22,10 +22,10 @@ class ResponseMassager {
   processInnerHitsProperties (response, sortOnEnumerationChronology) {
     response.hits.hits.forEach((hit) => {
       if (sortOnEnumerationChronology) {
-        hit._source.items.sort((a, b) => a.enumerationChronology_sort[0] > b.enumerationChronology_sort[0] ? -1 : 1)
+        hit._source.items.sort(sortOnPropWithUndefinedLast('enumerationChronology_sort'))
       }
       // Process "items" inner_hits
-      if (hit.inner_hits && hit.inner_hits.items) {
+      if (hit?.inner_hits?.items) {
         // Reassign items inner_hits to .items
         hit._source.items = hit.inner_hits.items.hits.hits.map((itemHit) => itemHit._source)
 
@@ -40,7 +40,7 @@ class ResponseMassager {
         hit._source.numItemsTotal = [unfilteredItems.hits.total]
       }
       // Process "electronicResources" inner_hits
-      if (hit.inner_hits && hit.inner_hits.electronicResources) {
+      if (hit?.inner_hits?.electronicResources) {
         // If record doesn't have indexed electronicResources...
         if (!hit._source.electronicResources || hit._source.electronicResources.length === 0) {
           // Gather up all records in the electronicResources inner_hit,

lib/util.js

@@ -1,6 +1,10 @@
 const logger = require('./logger')
 const isItemNyplOwned = require('./ownership_determination').isItemNyplOwned
 
+exports.sortOnPropWithUndefinedLast = (property) => {
+  return (a, b) => a[property]?.[0] || Number.MAX_SAFE_INTEGER > b[property]?.[0] || Number.MAX_SAFE_INTEGER ? -1 : 1
+}
+
 exports.buildJsonLdContext = function (prefixes) {
   const context = JSON.parse(JSON.stringify(prefixes))
   delete context.urn