Partial isotropic remeshing fails on debug builds

My understanding from the documentation is that you should be able to remesh a triangulated portion of a polygonal mesh. [This](https://github.com/user-attachments/files/26376585/cgal_test.zip) small test application attempts to remesh part of a polygonal prism after triangulating it and fails on debug builds with: ``` terminate called after throwing an instance of 'CGAL::Precondition_exception' what(): CGAL ERROR: precondition violation! Expr: CGAL::is_triangle(halfedge(f, tm), tm) File: /home/dimitris/source/gc/build/cgal/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/shape_predicates.h Line: 200 Aborted ``` It seems to work fine on release builds.