simulation: allow possibility to not create profit and loss movement

product/ERP5/mixin/rule.py

@@ -475,6 +475,7 @@ class RuleMixin(Predicate):
       else:
         # We must create a profit and loss movement
         new_movement = self._newProfitAndLossMovement(prevision_movement)
+        if new_movement is not None:
           movement_collection_diff.addNewMovement(new_movement)
 
 InitializeClass(RuleMixin)