I'm not sure you can so easily calculate 'error' for most real world cases.

In your example you are calculating error as a function of missed tests, for example. That's a pretty good example, you can't just leave that value at 2.5% of starting. It needs to be zero. All existing loops have logic to not proceed until those tests all pass.

If you can propose a means of generating an error signal in actual code you've just invented a way of automatically grading the goodness of code, which should make you quite a lot of money!