Screen A has a button in the lower right corner that closes screen A, removing all the buttons and other features of it, and goes to screen B. The listener routine for that button is protected so that it only acts on the “began” phase. Nevertheless, that listener is still seeing “moved” phase events for a button that should no longer exist! (And is no longer visible.) And sometimes, those moved events trigger this very uninformative stack trace, shown below. The one meaningful line number given, 160, refers to this code:
controlSlider:setValue(100*degreeOfControl)
My code does not reference contentWidth anywhere, and the other line references are so inscrutable that I really can’t figure out what’s going on. Help!
Istack traceback:
[C]: ?
?: in function <?:225>
(tail call): ?
…sers/Ken/Desktop/Programs/Corona/Nice Dice/setup.lua:160: in function ‘_listener’
?: in function <?:141>
?: in function <?:218>
2014-03-13 09:12:57.364 Corona Simulator[3657:d03] Runtime error
?:0: attempt to perform arithmetic on field ‘contentWidth’ (a nil value)(null)