This seems to indicate that the value of the selected mesh’s rotation is not valid. Can you check if selectedMesh.rotation exists? I think you mentioned working with React, so it might be that the state is not being properly kept between refreshes, or any other number of things.
@carolhmj I added a console log before the operation and confirmed that rotation.y exists and contains a value.
It will be good if you can share a reproduction of your React project then