[2.0.15] surface.platform.starter_pack read is nil

[Quezler]

run this command on an existing platform, a newly built platform, on a new platform in a new world, and it'll return nil:

`/c game.print(game.player.selected.surface.platform.starter_pack)`

the description states "The starter pack used to create this space platform.", but it SpacePlatform.hpp:238 suggests it'll be nilled once the pack got applied.

it would be nice if it could actually return the item & quality of the item that *got used* to create the platform, but if not a ? should be added and the text probably changed to something like this: "The starter pack that will be used to create this space platform."