notification: Add some exception handlings.
notification: Add some exception handlings.

In getProject() and resourceExists(), throw an exception if the current
resource type is unknown or unsupported.

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