I accept the fact that at times mistakes happen. I always read through a pattern before starting, if something doesn't seem quite right, or there is a typo or illustration error I fix it before beginning ( if I can figure out how) if I'm making a block that is new to me ( technique or design) I make a practice block before using my intended fabrics. When I find errors I visit the website ( if available) check for their ( fixes/errors) link ( they usually have one) to see if fixes have been posted. If the error has not yet been reported I contact them ( either the designer or the publisher) and report the error so they can note the error & fix on their site. Sometimes I check the site for errors before even buying a pattern. Seems like a ( community service) to check & report errors-- even a tested pattern can wind up incorrect due to an editing error.