Empty levels should always be dropped when checking the categorical target variables. Previously, levels were not being dropped when the subset argument is NULL. However, when Calibrate calls categoricalTargets, the default value of subset is NULL, so that any empty categories would not be dropped. Empty categories cause errors when calling rake from the survey package. Users using the widget would never have encountered this error because the widget always passes a non-null value for subset.

Ensure weights normalized prior to checking for trims