Added case when seq scan pred is null.
Added case when seq scan pred is null.

vittvolt/peloton,seojungmin/peloton,wangziqi2016/peloton,AngLi-Leon/peloton,vittvolt/15721-peloton,cmu-db/peloton,cmu-db/peloton,haojin2/peloton,vittvolt/15721-peloton,AngLi-Leon/peloton,AngLi-Leon/peloton,PauloAmora/peloton,prashasthip/peloton,eric-haibin-lin/peloton-1,vittvolt/15721-peloton,apavlo/peloton,seojungmin/peloton,ShuxinLin/peloton,PauloAmora/peloton,phisiart/peloton-p3,ShuxinLin/peloton,AllisonWang/peloton,malin1993ml/peloton,haojin2/peloton,AllisonWang/peloton,cmu-db/peloton,AllisonWang/peloton,apavlo/peloton,phisiart/peloton-p3,AngLi-Leon/peloton,wangziqi2016/peloton,jessesleeping/iso_peloton,vittvolt/peloton,yingjunwu/peloton,apavlo/peloton,AllisonWang/peloton,PauloAmora/peloton,prashasthip/peloton,seojungmin/peloton,jessesleeping/iso_peloton,apavlo/peloton,AngLi-Leon/peloton,AllisonWang/peloton,PauloAmora/peloton,malin1993ml/peloton,vittvolt/15721-peloton,phisiart/peloton-p3,malin1993ml/peloton,cmu-db/peloton,phisiart/peloton-p3,wangziqi2016/peloton,cmu-db/peloton,eric-haibin-lin/peloton-1,vittvolt/peloton,yingjunwu/peloton,vittvolt/15721-peloton,apavlo/peloton,eric-haibin-lin/peloton-1,ShuxinLin/peloton,vittvolt/peloton,yingjunwu/peloton,malin1993ml/peloton,haojin2/peloton,phisiart/peloton-p3,wangziqi2016/peloton,vittvolt/15721-peloton,malin1993ml/peloton,jessesleeping/iso_peloton,jessesleeping/iso_peloton,seojungmin/peloton,vittvolt/peloton,PauloAmora/peloton,ShuxinLin/peloton,prashasthip/peloton,yingjunwu/peloton,yingjunwu/peloton,seojungmin/peloton,apavlo/peloton,seojungmin/peloton,cmu-db/peloton,malin1993ml/peloton,AngLi-Leon/peloton,jessesleeping/iso_peloton,ShuxinLin/peloton,haojin2/peloton,eric-haibin-lin/peloton-1,jessesleeping/iso_peloton,prashasthip/peloton,ShuxinLin/peloton,phisiart/peloton-p3,wangziqi2016/peloton,eric-haibin-lin/peloton-1,AllisonWang/peloton,prashasthip/peloton,jessesleeping/iso_peloton,wangziqi2016/peloton,prashasthip/peloton,vittvolt/peloton,PauloAmora/peloton,haojin2/peloton,eric-haibin-lin/peloton-1,haojin2/peloton,yingjunwu/peloton