explicitly handle 0 column case to avoid instantiation errors when us…

…ed with jitted version of Book

roofit/RDataFrameHelpers/inc/RooAbsDataHelper.h

@@ -119,6 +119,16 @@ class RooAbsDataHelper : public ROOT::Detail::RDF::RActionImpl<RooAbsDataHelper<
  ///
  /// \param slot When IMT is used, this is a number in the range [0, nSlots) to fill lock free.
  /// \param values x, y, z, ... coordinates of the event.
+
+ // 0 column version
+ void Exec(unsigned int)
+ {
+ if (_eventSize) {
+ throw std::invalid_argument(std::string("RooDataSet can hold ") + std::to_string(_eventSize) +
+ " variables per event, but RDataFrame passed 0 columns.");
+ }
+ }
+
  template <typename... ColumnTypes>
  void Exec(unsigned int slot, ColumnTypes... values)
  {