I doing agree, it is not a javascript error ! again if i take the array exemple and the following code :

    var a = [1,2,3,4]
    // now i filter the array
    var b = a.filter(function(a){return a<0} );
    // b = []
    // now do something on b
    b.forEach(function(e){console.log(e)})
    // will "fail" silently , because it will output nothing

is what i'm doing stupid ? yes, but it is 100% valid from a javascript perspective. It is a coding error , but not a JS error.