L2SS-398: update archiving notebook and bug fix

devices/toolkit/archiver.py

@@ -300,7 +300,7 @@ class Archiver():
             es_list = self.get_subscribers()      
         for es_name in es_list:
             es = DeviceProxy(es_name)
-            attrs.extend(es.AttributeList)
+            attrs.extend(list(es.AttributeList or []))
         return attrs
     
     def get_subscriber_errors(self,es_name:str = None):
@@ -315,8 +315,8 @@ class Archiver():
             es_list = self.get_subscribers()
         for es_name in es_list:
             es = DeviceProxy(es_name)
-            attrs.extend(es.AttributeList)
-            errs.extend(es.AttributeErrorList)
+            attrs.extend(list(es.AttributeList or []))
+            errs.extend(list(es.AttributeErrorList or []))
         return dict((a,e) for a,e in zip(attrs,errs) if e) or {}
    
     def get_attribute_errors(self,attribute_name:str):