Hi, I'm using the Experimental version 2.1.21 of Factorio and your mod; after the rocket delivers to the platform, the game crashes with this error:

Error while running event CircuitLaunchableRockets::on_tick (ID 0)
CircuitLaunchableRockets/control.lua:427: attempt to index field 'import_from' (a nil value)
stack traceback:
CircuitLaunchableRockets/control.lua:427: in function 'get_rocket_destination'
CircuitLaunchableRockets/control.lua:334: in function <CircuitLaunchableRockets/control.lua:108>

I couldn't reproduce this myself but there is a pretty logical reason why it was happening so I hopefully fixed it.