Merge pull request #4651 from /issues/4650-crash-reloading-rows

Reader: Adds nil check before reloading row for updated attachments.

Author: aerych

WordPress/Classes/ViewRelated/Reader/ReaderCommentsViewController.m

@@ -1124,6 +1124,10 @@ - (void)commentView:(CommentContentView *)commentView updatedAttachmentViewsForP
 {
     Comment *comment = (Comment *)contentProvider;
     NSIndexPath *indexPath = [self.tableViewHandler.resultsController indexPathForObject:comment];
+    if (!indexPath) {
+        return;
+    }
+
     [self.tableViewHandler invalidateCachedRowHeightAtIndexPath:indexPath];
 
     // HACK: