Mark Signal.signal as optional

[sparr]

https://lua-api.factorio.com/latest/cla ... get_signal says "Returned Signal will not contain signal if none is set for the index." but https://lua-api.factorio.com/latest/con ... tml#Signal doesn't mark the signal field as optional. I think the type of Signal.signal should be SignalID? instead of SignalID

[curiosity]

Absolutely not. Other places guarantee the signal field exists, not to mention it's mandatory for write. The function should return a different type.
(although I question the utility of returning anything other than nil in that case, but that's an API change)

[robot256]

Right, the docs should be changed so that the return type of "get_signal" is "Signal or { }" for example.

[Bilka]

This is solved for 2.0.