issue: Fix NPE occurs when query string is empty.
issue: Fix NPE occurs when query string is empty.

ChangsungKim/TestRepository01,violetag/demo,naver/yobi,oolso/yobi,doortts/fork-yobi,yona-projects/yona,bloodybear/yona,ihoneymon/yobi,doortts/fork-yobi,doortts/forked-for-history,doortts/forked-for-history,bloodybear/yona,Limseunghwan/oss,oolso/yobi,Limseunghwan/oss,doortts/forked-for-history,naver/yobi,ahb0327/yobi,ChangsungKim/TestRepository01,brainagenet/yobi,yona-projects/yona,naver/yobi,yona-projects/yona,ihoneymon/yobi,ahb0327/yobi,oolso/yobi,bloodybear/yona,bloodybear/yona,ihoneymon/yobi,ahb0327/yobi,brainagenet/yobi,violetag/demo,yona-projects/yona,Limseunghwan/oss,doortts/fork-yobi,doortts/fork-yobi,brainagenet/yobi