Hey got an error when deleting the chest while an items was transfering:
error message:
The mod Orbital Transfer (0.1.2) caused a non-recoverable error. Please report this error to the mod author.
Error while running event orbital-transfer::on_tick (ID 0)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__orbital-transfer/control.lua:331 in function 'handleOutboundDeliveryTick'
orbital-transfer/control.lua:379: in function <orbital-transfer/control.lua:366>

reproduction steps:
Place chests => request items => Delete chest while item is in transit
==> Error

Ah, I think I see the problem, I'm not checking for validity when I try and switch the item to the target surface.

I'll fix this for the next version (most likely today), thanks!

Fixed (hopefully, anyway) in 0.2.0, let me know if it happens again.