Downloads bug for negative rules

Hello,

First let me see if i'm doing this right. I have a visitor level which is not allowed access to any downloadable content. Then I have another level to allow download of some of the protected groups (for the downloadables). So I have setup a negative rule for visitors where i have checked all the groups. This works fine. For the other level, I have set negative rules for the groups which should not be allowed access. If i understood correctly the groups that are unticked should be available to this user level, correct?

However, I have tried to download a file ( which is in a group that is not selected in negative rules ) using a user in that level, and it's not allowing me access.

I have then gone into your membership plugin code to find the issue with the following method: Membership_Rule_Downloads::can_view_download

You see, in that function you check for the rules but it does not always return true or false, sometimes it returns NULL as that situation is not handled. I had to add a couple of elses for the ifs to get it working. Now my main question is why is it like that?

Did I do something wrong about the rules or is it an actual bug?

Thanks.