[JS]fix js test load module example

[zhreshold]

Fix the js example which isn't working at all.
JS tvm.ndarray.length is undefined, indexing like A[i] with tvm.ndarray is not defined as well.
So the block

for (var i = 0; i < B.length; ++i) {
    tvm.assert(B[i] == A[i] + 1);
}

was not entered at all.

Also fixing an error when the script is trying to generate js library where options are not properly set.