Why the hell this crashes in UICollectionView?

dummy.swift

let expandedSections = [0, 3, 8]
let indexSet = IndexSet(expandedSections)

		collectionView?.performBatchUpdates(
			{
				[unowned self] in
				if isInserted {
					self.collectionView?.insertItems(at: indexPaths)
				} else {
					self.collectionView?.deleteItems(at: indexPaths)
				}
				if !indexSet.isEmpty {
					self.collectionView?.reloadSections(indexSet)
				}

			}, completion: {
				_ in
			}

2 years later, I have the answer. Happens when you do this:

let indexPath = IndexPath(item: NSNotFound, section: section)
let attr = UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, with: indexPath)

and somewhere along the way you do collectionView.reloadSections()

Problem is indexPath, which should be:

let indexPath = IndexPath(item: 0, section: section)

Hi I'm facing the same issue using framework for CollectionView well that is weird.
Thanks for posting the reason why it happens.
Although i did not understand fully why this is happening.
My only hint is that somehow indexSet is over-floating.