Since each control point will call this when the path updates, the previous would correct the start segment 3 times instead of just once.
This fixes that.
Here we produce a local bound copy of the path version, and bind it to update the path type.
This way, if the path version updates (i.e. any control point changes type or position), we check that all control points have a well-defined path.
Additionally, if the control point piece is disposed of, the GB should also swoop up the subscription because of the local bound copy.