You really did not fix it if you used "
==" in
{w.label == "_";}the above statement is actually not an assignment to the label but instead just evaluating the condition which reports
true if the label of the widget matches "
-"
Hoping this is just copy/paste or retype error on your part.
A better approach along to set the label to "-" if timer is not numeric is:
if (isNaN(hallLightsTimer)) {w.label ="-";}
[Link: w3schools.com]