WASHINGTON — The Supreme Court today said an Internet search site that posted false information about people can be sued only if the errors caused actual harm.The 6-2 ruling is a narrow victory for the search service Spokeo.com and other technology firms seeking to avoid costly litigation over the publication of inaccurate data.The justices threw out an appeals court ruling in favor of Thomas Robins, a Virginia resident who sued Spokeo after it posted an online profile about him that was riddled with errors about his …