nil check before size > 0 fixes #1949
nil check before size > 0 fixes #1949

nyimbi/cartodb,bloomberg/cartodb,thorncp/cartodb,codeandtheory/cartodb,thorncp/cartodb,raquel-ucl/cartodb,nuxcode/cartodb,UCL-ShippingGroup/cartodb-1,nyimbi/cartodb,DigitalCoder/cartodb,codeandtheory/cartodb,future-analytics/cartodb,bloomberg/cartodb,codeandtheory/cartodb,bloomberg/cartodb,nuxcode/cartodb,DigitalCoder/cartodb,nuxcode/cartodb,dbirchak/cartodb,splashblot/dronedb,raquel-ucl/cartodb,nyimbi/cartodb,dbirchak/cartodb,CartoDB/cartodb,future-analytics/cartodb,nuxcode/cartodb,splashblot/dronedb,splashblot/dronedb,bloomberg/cartodb,thorncp/cartodb,thorncp/cartodb,UCL-ShippingGroup/cartodb-1,splashblot/dronedb,CartoDB/cartodb,codeandtheory/cartodb,UCL-ShippingGroup/cartodb-1,dbirchak/cartodb,raquel-ucl/cartodb,DigitalCoder/cartodb,dbirchak/cartodb,UCL-ShippingGroup/cartodb-1,nyimbi/cartodb,nuxcode/cartodb,DigitalCoder/cartodb,codeandtheory/cartodb,DigitalCoder/cartodb,dbirchak/cartodb,nyimbi/cartodb,future-analytics/cartodb,splashblot/dronedb,UCL-ShippingGroup/cartodb-1,CartoDB/cartodb,raquel-ucl/cartodb,raquel-ucl/cartodb,bloomberg/cartodb,thorncp/cartodb,future-analytics/cartodb,CartoDB/cartodb,CartoDB/cartodb,future-analytics/cartodb