[FIX] Fixing issue with empty BAM files and bam_library_size demo.
[FIX] Fixing issue with empty BAM files and bam_library_size demo.

JohnReid/seqan,ktrappe/seqan,xp3i4/seqan,JohnReid/seqan,JohnReid/seqan,PF2-pasteur-fr/seqan,budach/seqan,hannespetur/SeqAnHTS,xp3i4/seqan,ktrappe/seqan,catkira/seqan,bayolau/seqan,catkira/seqan,JohnReid/seqan,limeng12/seqan,xp3i4/seqan,hannespetur/SeqAnHTS,budach/seqan,xenigmax/seqan,bestrauc/seqan,xp3i4/seqan,ktrappe/seqan,JohnReid/seqan,xenigmax/seqan,ktrappe/seqan,catkira/seqan,ktrappe/seqan,limeng12/seqan,xenigmax/seqan,PF2-pasteur-fr/seqan,catkira/seqan,bestrauc/seqan,PF2-pasteur-fr/seqan,catkira/seqan,budach/seqan,xenigmax/seqan,xenigmax/seqan,budach/seqan,hannespetur/SeqAnHTS,limeng12/seqan,catkira/seqan,xp3i4/seqan,hannespetur/SeqAnHTS,bayolau/seqan,limeng12/seqan,ktrappe/seqan,hannespetur/SeqAnHTS,limeng12/seqan,bestrauc/seqan,hannespetur/SeqAnHTS,bestrauc/seqan,PF2-pasteur-fr/seqan,xenigmax/seqan,bayolau/seqan,catkira/seqan,JohnReid/seqan,budach/seqan,bestrauc/seqan,limeng12/seqan,budach/seqan,budach/seqan,bayolau/seqan,ktrappe/seqan,budach/seqan,xp3i4/seqan,PF2-pasteur-fr/seqan,xp3i4/seqan,JohnReid/seqan,bestrauc/seqan,JohnReid/seqan,bayolau/seqan,catkira/seqan,bayolau/seqan,JohnReid/seqan,PF2-pasteur-fr/seqan,PF2-pasteur-fr/seqan,ktrappe/seqan,bayolau/seqan,PF2-pasteur-fr/seqan,limeng12/seqan,xenigmax/seqan,PF2-pasteur-fr/seqan,ktrappe/seqan,hannespetur/SeqAnHTS,xp3i4/seqan,limeng12/seqan,limeng12/seqan,budach/seqan,hannespetur/SeqAnHTS,xp3i4/seqan,bestrauc/seqan,hannespetur/SeqAnHTS,bayolau/seqan,xenigmax/seqan,catkira/seqan,bestrauc/seqan,bayolau/seqan