Very sorry about this but I have searched the forum with no result - must be using the wrong search parameters.
Any undeclared variable is only coming up as a warning - and it does not stop the compilation. The problem is, warning means spell errors tend to get through unnoticed.
I want it to show undeclared variable as an error - is this possible (and underline in red).
My only suggest is to keep and eye on the warnings and look for unused variables.
I know which technically you should always look at warnings - but during development they can be a bit overwhelming and sometime not applicable to the final project.