We may raise false positives when one of the operands is an ``++Object++``. An ``++Object++`` which wraps some kind of number may have a valid ``++valueOf++`` method: see https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/valueOf#Examples[an example].
If we see that we raise too many false positives, we can:
* raise an issue only on some kinds of ``++Object++`` for which we know that there is a problem: ``++Array++``, ``++Date++``, ``++Function++``, ``++Regexp++``
* keep the same exception on ``+`` for these kinds of operand
More detailed message: "The value of this operand is (undefined|an object) on at least one path of execution. Refactor the code to avoid having NaN ("Not a Number") as the result of the parent expression."
