i still don't understand. is it easier in python or JS to make getters and setters? with python my experience has been the opposite, with the decorator based solution in mind.
or if the problem is that they exist, as an option to be used, why is that a problem? they can be implemented in any other language, and it can be useful.

then yeah, you should check for nulls. just like for None's in python, or if you have the correct type at all, because if it's entirely different but ends up having a function or variable with the same name then who knows what happens.
then in javascript besides null, you also have undefined and NaN!