Adds getattr to permission_set_ids on the permission_set issue (#9)

target_salesforce_v3/client.py

@@ -371,7 +371,7 @@ def add_custom_field(self,cf,label=None):
             # But then, we need to add the permissions to the Task sObject
             # So we change it back again from `Activity` -> `Task`
             sobject = 'Task'
-        for permission_set_id in self.permission_set_ids:
+        for permission_set_id in getattr(self, "permission_set_ids", []):
             self.update_field_permissions(permission_set_id, sobject_type=sobject, field_name=f"{sobject}.{cf}")
 
     def update_field_permissions(self,permission_set_id, sobject_type, field_name):