Joe,
So what is your widget development workflow. The one that I use consistently is start basic boilerplate development in [install dir]\client\stemapp\widgets. Then create a new app for further development (i.e. app name widget x) then I add the new widget to that app. All further code changes and work now occurs in the [install dir]/server/apps/[app #]/widgets/widgetX folder and changes to the config now have to be made to the [install dir]/server/apps/[app #]/configs/widgetX/config_widgetX.json AND the [install dir]/server/apps/[app #]/widgets/widgetX/config.json (so that when I copy the [install dir]/server/apps/[app #]/widgets/widgetX back to the [install dir]\client\stemapp\widgets folder for new apps, it has the same changes in the config.json).
It sounds like you have some code in the Widget.js or the Settings.js that is still referencing servicePath. Normally I have code that checks for the existence of the config property before I try and use it in my code.