The error message seems fairly straightforward. It seems that it’s trying to find a variable in your Elevator asset named Widget but it doesn’t exist. As it suggests, is it possible that Elevator used to inherit from something that included a Widget variable that it no longer inherits from? Possibly the class it inherits from no longer has that variable?
Edit: None of these are error messages actually, they’re only warnings and shouldn’t block your packaging attempts. Could you supply the full log file?