Hi Pilou, well I guess yes that is a bug but it's not really one that's worth fixing because you have invalid input there and the bug fix would be to just do nothing there at all.

The diameter is the distance across here:


The thickness is the distance across this area:



Notice how the diameter travels across 2 walls? That means the diameter must be greater than 2 times the wall thickness for a pipe to be structured properly.

You've got both outer diameter and thickness equal and so that's not valid input for defining a pipe in this way. Just don't use that invalid input and you should not see the error anymore.

- Michael