When programmers code faulty software then it usually fails to do its job. What you are suggesting is that humans succeed at creating the seed for an artificial intelligence with the incentive necessary to correct its own errors. It will know what constitutes an error based on some goal-oriented framework against which it can measure its effectiveness. Yet given this monumental achievement that includes the deliberate implementation of the urge to self-improve and the ability quantify its success, you cherry-pick the one possibility where somehow all this turns out to work except that the AI does not stop at a certain point but goes on to consume the universe? Why would it care to do so? Do you think it is that simple to tell it to improve itself yet hard to tell it when to stop? I believe it is vice versa, that it is really hard to get it to self-improve and very easy to constrain this urge.