fix test case wrong if clause

nucleus/southbound_test.go

@@ -166,8 +166,8 @@ func Test_unmarshal(t *testing.T) {
 			}
 			bytes := resp.Notification[0].Update[0].Val.GetJsonIetfVal()
 			oc, err := NewSBI(spb.Type_TYPE_OPENCONFIG)
-			if (err != nil) != tt.wantErr {
-				t.Errorf("Unmarshal() error = %v, wantErr %v", err, tt.wantErr)
+			if err != nil {
+				t.Errorf("unmarshal() error = %v", err)
 				return
 			}