So when creating param files for the fast simulation we make and write many TFCSParametrizationChain objects to a root file. This was causing a seg fault, coming from the streamer of TFCSParametrizationChain.
I asked for help on the root forum, where pcanal gave an excellent explanation; objects owned by
m_chain were also being given to a
unique_ptr, such that delete was called on the data twice.
I tested this fix by making and running a large param file and it worked.