Well, I had to replace more than one node in the past because new versions didn't support the features I used.
So the question is: will this work in the future?
@cflurin variables defined in the on start should not be directly accessible in the on message tab.
The fact you can define functions like that and have pad and timestamp available in the on message tab is a bug and will be fixed. I'm not even sure how that is possible.
The correct way to define things in on start to reuse in on message is via the context object.