It's next to impossible to have an error-free book. There're too many people and steps involved where errors can be introduced into the process. Famously, the KJV Bible had typos, and there were plenty of scholars checking it. I find typos, missed punctuation, in most every book I read, more so with books published since the '90's. I think publishers are less concerned about editing these days, and then there're the self-publishers.