Merge pull request #4223 from Vito0912/feat/fixCrashEmptyCollection

Fix server crash when a user requests the RSS feed of an empty collection

server/models/FeedEpisode.js

@@ -215,9 +215,13 @@ class FeedEpisode extends Model {
    * @returns {Promise<FeedEpisode[]>}
    */
   static async createFromBooks(books, feed, slug, transaction) {
-    const earliestLibraryItemCreatedAt = books.reduce((earliest, book) => {
+    // This is never null unless the books array is empty, as this method is not invoked when no books. Reduce needs an initial item
+    const earliestLibraryItemCreatedAt =
+      books.length > 0
+        ? books.reduce((earliest, book) => {
             return book.libraryItem.createdAt < earliest.libraryItem.createdAt ? book : earliest
           }).libraryItem.createdAt
+        : null
 
     const feedEpisodeObjs = []
     let numExisting = 0