public function destroy($bookSlug, $chapterSlug)
{
$book = $this->bookRepo->getBySlug($bookSlug);
$chapter = $this->chapterRepo->getBySlug($chapterSlug, $book->id);
$this->checkOwnablePermission('chapter-delete', $chapter);
Activity::addMessage('chapter_delete', $book->id, $chapter->name);
$this->chapterRepo->destroy($chapter);
return redirect($book->getUrl());
}