This is, I guess, not really this spoon problem, but rather a problem that should be addressed upstream.
Still, there an issue that maybe you can help to solve: spoon doesn't work when trying to toggle dark mode, my guess, because Hammerspoon doesn't ask for permissions to automate System Events.app or it asks but because this feature is released in a half-broken state in Mojave, it bugs for some reason.
This is, I guess, not really this spoon problem, but rather a problem that should be addressed upstream. Still, there an issue that maybe you can help to solve: spoon doesn't work when trying to toggle dark mode, my guess, because Hammerspoon doesn't ask for permissions to automate System Events.app or it asks but because this feature is released in a half-broken state in Mojave, it bugs for some reason.