MCTruthSimAlgs: Make sure the GenVertexPtr is not null before dereferencing it
The title explains it all. I think this was overlooked in !39619 (merged).
Closes ATLASSIM-5070
cc: @jchapman
The title explains it all. I think this was overlooked in !39619 (merged).
Closes ATLASSIM-5070
cc: @jchapman