mvcc: go style err check (#11419)
mvcc: go style err check (#11419)


coreos/etcd,cockroachdb/etcd,ajityagaty/etcd,mqliang/etcd,rnaveiras/etcd,mqliang/etcd,mqliang/etcd,dannysauer/etcd,coreos/etcd,li-ang/etcd,mkumatag/etcd,li-ang/etcd,gyuho/etcd,ajityagaty/etcd,etcd-io/etcd,ajityagaty/etcd,rnaveiras/etcd,etcd-io/etcd,gyuho/etcd,cockroachdb/etcd,mkumatag/etcd,rnaveiras/etcd,etcd-io/etcd,mkumatag/etcd,dannysauer/etcd