Fix adding widgets with invalid config via app to home screen

[jpelgrom]

Summary

Found a small bug in the new option to add widgets to your home screen via the app: invalid configuration only causes an exception when trying to save the data. However, when adding them via the app, the app will try saving the data after asking the launcher to add a widget, resulting in an error after adding a widget to the home screen and the widget on the home screen will never be updated.

This PR adjusts that process to check the variable/input that would typically cause the exception before asking the launcher to add a widget. Validation in general could be better, but at least now adding widgets from the app will match the behavior of adding widgets from the home screen.

(To test: add the updated widget without setting any values.)

Screenshots

n/a

Link to pull request in Documentation repository

n/a

Any other notes