Why are we busy trying to work out if you have to blame the inventor or the object?
1. By default it's the person who employs the object
e.g if a wheel falls off your car and kills someone, it's your fault
2. If you can prove someone else negligent then it's no longer your fault
e.g. A garage changed your tyre and didn't tighten up the bolts
If you are using an object and it's not fit for purpose then;
1. If you CHOSE to use the object, it's your fault
e.g. You selected an anesthetic which stopped a patents heart
2. If you had assurance for the supplier of the object it was fit for purpose then it's no longer your fault.
e.g. The anesthetic was mis-labelled
Even if a robot made decisions based on it's inputs, ownership of errors would still be based on who chose to use a robot and what assurances the supplier gave, this will only change if a robot became sentient (and even then, only if it could be responsible and punishable).