message: merge formData with current in Stepper onChange
diff: @@ -102,7 +102,8 @@ export const Stepper = (props: StepperProps) => {
  };
  const handleChange = useCallback(
  - (e: IChangeEvent) => setFormState(e.formData),
  + (e: IChangeEvent) =>
  + setFormState(current => ({ ...current, ...e.formData })),
  [setFormState],
  );
  