Also copying this into the discourse forums, the bug identified by Michael Pryor about a year ago still seems to be present in GH v1.0.0004; null items have weird effects on the basic arithmetic components: they are either treated as 0, 1, or even ‘0-’ (in the case of subtraction, where null - x = x). Division seems to treat an operation on a null item as an ‘illegal’ operation that returns another null…
I tested this with empty branches and the same occurred. I would anticipate any arithmetic operation on a null or empty branch produces again a null or empty branch, or triggers an error/warning?
Is there a better solution to this other than writing our own code blocks to deal with null items or empty branches?