I can't use any widget functions, I get this error when I try. attempt to index a nil value (global 'widget')
Without context, no one can help you. What kind of mod are you trying to make, what does your code look like? Personally, I don't know much aboug widget functions yet, but they may be similar to player functions in that they can only be called by certain types of scripts. So a tech mod, for example, would be unable to call any player functions, while a ScriptPane would be able. So it may just be that whatever you're doing doesn't have access. Also keep in mind, the current HUD widgets are hard-coded, as far as I understand it. While you can change the visual credentials of the widgets, you can't change their function, or add new ones. Hopefully this isn't true, though, as I would love to be able to add a proper tech screen for my own mod at some point.
I'm modifying the sign shop gui, I've added a widget and made it run a function in the lua file but the widget functions don't work at all.