check error in router_test

testing/scenarios/router_test.go

@@ -63,6 +63,7 @@ func TestRouter(t *testing.T) {
 		IP:   []byte{127, 0, 0, 1},
 		Port: int(50022),
 	})
+	assert.Error(err).IsNil()
 
 	payload = "blocked dokodemo request."
 	nBytes, err = conn.Write([]byte(payload))