Roof example fails

[DSchroer]

Running the roof sample fails with the following CGAL error:

CGAL error: precondition violation!
Expression : FPU_checker<Info>::is_valid()
File       : /emsdk/upstream/emscripten/cache/sysroot/include/CGAL/Straight_skeleton_2/Straight_skeleton_builder_traits_2_aux.h
Line       : 270
Explanation: 
Refer to the bug-reporting instructions at https://www.cgal.org/bug_report.html

@ochafik do you have any idea what could be causing this one?