I got that behaviour yesterday if I made a rail revolve that was incorrect and resulted in a little sliver down the axis of revolution...After the incorrect result, if you tried to select the sliver to get rid of it, the sidepain error.

Heres an example that I hope can help to find it. If you do a rail revolve with the top view plane curve using the smaller curve as the rail and down the center axis, you will get the sliver (I know it would be the intended result) But trying to select the little sliver gives the error.

FYI.

[EDIT] Same for me on the construction lines BTW [EDIT]