ERROR trying to derefernce nullptr

Users of Analysis Productions: If your production is affected by this problem please help debug it! To do this:

1. Read through this issue to see if the problem has already been understood
2. Create a (preferably minimal) reproducer and post here.
3. Edit the title and description of this issue to be more meaningful.

If you need help, a good place to ask would be: https://mattermost.web.cern.ch/lhcb/channels/davinci

The issue: This issue is being opened in response to issues in analysis productions.

The original match that triggered this was:

 BNOC_veryloose_lambda_LL              ERROR auto&& Sel::Utils::deref_if_ptr(T&&) [with T = const LHCb::VertexBase* const&] : trying to derefernce nullptr
 HLTControlFlowMgr                     FATAL Event failed in Node ThreeBodyCombiner/BNOC_bbaryon_3body_19cd708c
 HLTControlFlowMgr                      INFO Application return code set to 3
 HLTControlFlowMgr                     FATAL Event 11639 on slot 0 failed!
 HLTControlFlowMgr                     FATAL *** Too many consecutive failures 1, stopping now ***

See the linked issues in https://gitlab.cern.ch/lhcb-datapkg/AnalysisProductions/ for more details.