in reply to
While the warning does point me in the right direction, on lines with many variables being used at once, it can take a bit of work to figure out exactly which one is undefined. Is there a way to get more explicit information from warnings like these?
One should realize that the warning is generated at runtime -
not at compile time. At that moment, the name of the variable is hard to get, and (even more important), the
undefined value could come from a complicated expression.