If navigational software is a service, its producer won't be liable unless the producer is negligent. If the producer took every imaginable precaution, the producer can't be negligent. In the case of products, the existence of a defect is enough by itself to impose liability. Nevertheless, no legislature or court ever bothered to tell us what is and is not a product in the context of strict liability law. Under the Uniform Commercial Code, a product is a thing, movable at the time of a transaction.
Services are everything else.
That's some help, but perhaps not much. The code says that a bottle of aspirin or a mobile home are movable things, and therefore goods. An architect's services may be movable, but they aren't things, so they aren't goods. They are movable things and, if they're wrong, they can cause damage. The British invented the goods-services distinction in the 17th century.