Understand std::bad_alloc cash in dilepon histmaker for unfoldig #549
Description
Running the following command lead to a seg fault:
python scripts/histmakers/mz_dilepton.py --dataPath /scratch/shared/NanoAOD/ --analysisMode unfolding --maxFiles 10 --forceDefaultName -o /scratch/dwalter/results_histmaker/test/ --axes ptll yll --genAxes ptVGen absYVGen --postfix unfolding --filterProcs Zmumu -v 4 --noAuxiliaryHistograms
It was found that it doesn't crash wen inverting the dataset order, maybe some undefined behaviour. A temporary fix is done in #542
We have to understand why this is happening.