Ensure download method only fiddles with what the flags points it should

[avengerx]

According to Microsoft Documentation on the DownloadEffect function, the dwFlags argument determines what's being fed by the downloaded effect. So that we can skip checking for null pointers, sizes, if the flag indicates a given variable of an effect is not to be updated or has been passed.

This should help return early with invalid params in case a required parameter flag is not passed, or simply return early if nothing is to be changed.