In most professions it's called "errors and omissions" or malpractice insurance. Common, necessary, and typically expensive. But it often doesn't protect the individual as much as it does the company - paying for the result of the error or omission to keep minor issues from causing bankruptcy when the lawyers are finished. The poor schlub who committed the e or o at best gets demoted and usually finds another line of work. And if it's an individual practice insurance is irrelevant - word gets around fast whether or not you made it good and you have no more clients: find another line of work.