check for nil

ruby/lib/jam_ruby/models/user.rb

@@ -673,22 +673,26 @@ module JamRuby
         OnlinePresence.delete_all(["user_id = ?", self.id])
       end
 
+      unless online_presences.nil?
         online_presences.each do |op|
           new_presence = OnlinePresence.create(self, op, false)      
           self.online_presences << new_presence
         end
       end
+    end
 
     def update_performance_samples(performance_samples)
       unless self.new_record?
         PerformanceSample.delete_all(["user_id = ?", self.id])
       end
 
+      unless performance_samples.nil?
         performance_samples.each do |ps|
           new_sample = PerformanceSample.create(self, ps, false)
           self.performance_samples << new_sample
         end
       end
+    end
 
     # given an array of instruments, update a user's instruments
     def update_instruments(instruments)