Added protection for empty SliceAdaptor->fetch_by_region
Added protection for empty SliceAdaptor->fetch_by_region

Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-draw