fix accounting

billard/models.py

@@ -56,6 +56,7 @@ class Client(models.Model):
 
     def accounting_for(self, desk_no, pht, pnt):
         t = Accounting.objects.filter(client_id=self.id, desk_no=desk_no)[:3][::-1]
+        if t.__len__() > 0:
             a = t[t.__len__() - 1]
             if a.time_to is None:
                 prize = utils.get_prize_for(start=a.time_from, end=datetime.now(timezone.utc), pph=pht)