Fix bug - when data-frame is empty, do not calculate the sum()
Fix bug - when data-frame is empty, do not calculate the sum()

crukci-bioinformatics/claritypy-ngsreports,crukci-bioinformatics/claritypy-ngsreports,pajanne/ngsreports,pajanne/ngsreports,crukci-bioinformatics/claritypy-ngsreports,pajanne/ngsreports