RNAseq PE: coverage calculation step fails workflow when no reads are aligned

[mvdbeek]

This seems rather unfortunate for large projects. Should we do $0~"Uniquely mapped reads number"{print 1000000/($NF+1)} instead in the get scaling factor step ? ping @lldelisle

[lldelisle]

I guess if it does not fail here, it will fail at the bigwig step... But I would prefer to do a if($NF == 0){print 0}