The NaN trap illustrated

oops1.js

function UnitTest() {
    const polar = Polar(3.0, 4.0);
    const expected_distance = 5.0;
    const diff = polar.distance - expected_distance;
    if (Math.abs(diff) > 1.0e-12) {
        console.error('ERROR: Excessive distance error: ', diff);
        return 1;
    }
    console.log('PASS');
    return 0;
}