Prevent report `split_by` use with invalid names or non-select-one questions.
Prevent report `split_by` use with invalid names or non-select-one questions.

kobotoolbox/kpi,kobotoolbox/kpi,kobotoolbox/kpi,onaio/kpi,onaio/kpi,onaio/kpi,kobotoolbox/kpi,onaio/kpi,kobotoolbox/kpi