Membership registration not working (bug)

Hi There,

I’m having trouble to get the registration page up and running. This is the message I get after filling in the fields:

Notice: Undefined variable: user_id in …/plugins/membership/membershipincludes/classes/membershippublic.php on line 1710

Can you please take a look at it. Looks like a workaround has been implemented but this line uses $user_id which has not been defined in case of an error.