I would think most patterns have a mistake or two. Most designers do have ( testers) follow the patterns, make the projects to find the errors before they go to the publisher, but sometimes something still gets missed, or even the publisher can make a typo, reverse a diagram etc. magazine editors sometimes change a pattern to fit the allowed space in the magazine and don’t realize they left out something important— it’s not always the designer’s error. errors happen. When an error is found don’t get upset- accept we are all human. Contact the designer & let them know. Often they have a place on their website for corrections. They appreciate you finding it and try to fix ASAP.