Fix bug in pegasus-statistics which manifests, because an unassugned variable is reference,  when output format is csv.
Fix bug in pegasus-statistics which manifests, because an unassugned variable is reference,  when output format is csv.

pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus