Octopus intelligent slots - avoid crash if empty

Better fix this time

Author: springfall2008

predbat.py

@@ -826,7 +826,9 @@ def update_pred(self):
 
         # Octopus intelligent slots
         if 'octopus_intelligent_slot' in self.args:
-            self.octopus_slots = self.get_state(entity_id = self.args['octopus_intelligent_slot'], attribute='completedDispatches')
+            completed = self.get_state(entity_id = self.args['octopus_intelligent_slot'], attribute='completedDispatches')
+            if completed:
+                self.octopus_slots += planned
             planned = self.get_state(entity_id = self.args['octopus_intelligent_slot'], attribute='plannedDispatches')
             if planned:
                 self.octopus_slots += planned