Nasty seg fault if you mess up the decay descriptor

I had the decay descriptors wrong in

#FunTuple: define branches
branches = {
    'Bs': "[B_s0 -> B0 pi+]CC",
    'pip': "[B_s0 -> B0 ^pi+]CC",
}

(I messed up the pip one) and was faced with

Tuple                               WARNING FunTupleBase<Gaudi::NamedRange_<std::vector<LHCb::Particle const*,std::allocator<LHCb::Particle const*> >,__gnu_cxx::__normal_iterator<LHCb::Particle const* const*,std::vector<LHCb::Particle const*,std::allocator<LHCb::Particle const*> > > > >:: update_counters: No candidates found in this event. Skipping this event
RFileCnv                               INFO opening Root file "tuple_hlt2.root" for writing
 *** Break *** segmentation violation

This took a while to debug ;)

Can there be a clearer error?