Merge pull request #4070 from woocommerce/issue/3369-media-crash-backport-6.5

[6.5 Backport] Prevent crash when the media library has exactly the same amount of items as the request page size

Author: koke

RELEASE-NOTES.txt

@@ -7,6 +7,7 @@
 6.5
 -----
 - [*] Fix: Product images with non-latin characters in filenames now will load correctly and won't break Media Library. [https://github.com/woocommerce/woocommerce-ios/pull/3935]
+- [*] Fix: The screen to select images from the Media Library would sometimes crash when the library had a specific number of images. [https://github.com/woocommerce/woocommerce-ios/pull/4070]
 
 6.4
 -----

WooCommerce/Classes/ViewRelated/Products/Media/WordPressMediaLibraryPickerDataSource.swift

@@ -177,6 +177,12 @@ private extension WordPressMediaLibraryPickerDataSource {
     /// Appends the new media items to the existing media items.
     ///
     func updateMediaItems(_ newMediaItems: [Media], pageNumber: Int, pageSize: Int) {
+        // If the response contains no new items, there is nothing to update.
+        // We return early since the code would generate an invalid range of indices to update otherwise.
+        guard newMediaItems.isNotEmpty else {
+            return
+        }
+
         let pageFirstIndex = syncingCoordinator.pageFirstIndex
         let mediaStartIndex = (pageNumber - pageFirstIndex) * pageSize
         let mediaStartIndexOfTheNextPage = (pageNumber + 1 - pageFirstIndex) * pageSize