Ok, sounds good.
I believe we need basic thread safety there, since we cannot guarantee isolated usage. But somewhat general locking is ok.
The problem with the line1/line2 above is clear, taking into account how we treat the script body. Namely all declarations become class level declarations, non-declaring statements going to the constructor body, and previous lines treated like implicit receivers. I’m not sure we can do much about it without changing concepts, or split lines into smaller pieces.