Automatic endpoint selection outside of surface module


I am trying to extract centerlines from vascular models using the automatic endpoint selection from the VMTK module in Slicer, and in some cases (I’d say in about 10-20% of cases) I come across an error which gets the centerline computation stuck:

Warning: In /Volumes/D/S/S-0-build/VTK/Common/DataModel/vtkPolyData.cxx, line 993 
vtkPolyData (0x7fe922612940): Building VTK_LINE 15 with only one point, but VTK_LINE needs at 
least two points. Check the input.

Investigating this issue, I found that this happens when at least one of the endpoints is placed outside of the volume closed by the surface model of the vascular structure in a given case, and I can avoid the issue by manually placing the problematic endpoint/s inside of the model. However, I want to keep the whole process automatic. Is there a way to fix that?

Thank you,

Of course, I meant surface model* in the topic. Sorry about that.