New to mods and haven't tried making one yet. It could perhaps be some incompatibility with some other mod I've loaded (nightvision should be vanilla), but if it is in the mod code I don't have the capabilities to try and fix it myself right now. Anyway, just got the following error: (As of this morning I'm running base v0.18.35 in case it matters.)

This mod Nightvision Toggles (1.0.1) caused a non-recoverable error. Please report this error to the mod author.

Error while running event NightvisionToggles::night-vision-toggle (ID 163)
LuaEquipment API call when LuaEquipment was invalid.
stack traceback:
[C]: in function 'take'
NightvisionToggles/control.lua:24: in function
<NightvisionToggles/control.lua:18>
stack traceback:
[C]: in ?
[C]: in function 'take'
NightvisionToggles/control.lua:24: in function
<NightvisionToggles/control.lua:18>

I think I know the problem, I'll have a look when I get off work.

Turns out I didn't know the problem, but it's fixed now. Sorry about that.

Thanks. Working great now.