If a blank scene is created by Navigathena when there is only one scene, unloading the previous scene will cause the active scene to switch to the blank scene.
As a solution to this problem, a method was proposed to make the scene loaded by Navigathena the active scene. #15

However, in principle, the active scene should be managed by the user, not Navigathena, so the solution is to always unload the blank scene and only switch the active scene in the above case.