handle index of empty files gracefully
handle index of empty files gracefully

wgerlach/Shock,wgerlach/Shock,MG-RAST/Shock,teharrison/Shock,MG-RAST/Shock,wgerlach/Shock,teharrison/Shock,teharrison/Shock,teharrison/Shock,wgerlach/Shock,MG-RAST/Shock,MG-RAST/Shock,teharrison/Shock,MG-RAST/Shock,wgerlach/Shock,teharrison/Shock