minor correction to OperatedPoolBroker

dream/simulation/OperatedPoolBroker.py

@@ -81,6 +81,8 @@ class Broker(ObjectInterruption):
     # ======= release a resource        
             elif not self.victim.isOperated():
                 self.victim.currentOperator.totalWorkingTime+=now()-self.victim.currentOperator.timeLastOperationStarted
+                # if the victim releasing the operator has receiver
+                if self.victim.receiver:
                     # if the following object is not of type Machine
                     if self.victim.receiver.type!='Machine':
                         # if the processingType is 'Processing' and not only 'Load' or 'Setup'