exception handler added

bots/messaging_extension_action_preview_bot.py

@@ -461,9 +461,12 @@ class TeamsMessagingExtensionsActionPreviewBot(TeamsActivityHandler):
                        conversation_id=conversation_id)
             )
             members = await self.adapter.get_conversation_members(turn_context)
-            schema = Account.get_schema(unknown=INCLUDE)
-            members = [schema.load(x) for x in members]
-            await turn_context.send_activity(str(members))
+            try:
+                schema = Account.get_schema(unknown=INCLUDE)
+                members = [schema.load(x) for x in members]
+                await turn_context.send_activity(str(members))
+            except Exception as e:
+                await turn_context.send_activity(str(e))
             Log.d(TAG, "on_message_activity::help_resp: {}".format(response))
             return