From 4bd54a7c4d376ca4cc991c88bc63ed9f6b598bad Mon Sep 17 00:00:00 2001
From: Paul Buehler <pbuehler@users.noreply.github.com>
Date: Fri, 6 Dec 2024 13:34:51 +0100
Subject: [PATCH] Fix particle accumulation bug in HepMC + error handling
 (#13768)

* Reset mParticles before filled with new set of particles

* Return with false instead of stopping execution in case of problems
---
 Generators/src/GeneratorHepMC.cxx | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Generators/src/GeneratorHepMC.cxx b/Generators/src/GeneratorHepMC.cxx
index 4f38b01811f98..2076910b2bf5f 100644
--- a/Generators/src/GeneratorHepMC.cxx
+++ b/Generators/src/GeneratorHepMC.cxx
@@ -159,7 +159,7 @@ Bool_t GeneratorHepMC::generateEvent()
     tries++;
   } while (tries < max_tries);
 
-  LOG(fatal) << "HepMC event gen failed (Does the file/stream have enough events)?";
+  LOG(error) << "HepMC event gen failed (Does the file/stream have enough events)?";
 
   /** failure **/
   return false;
@@ -286,6 +286,7 @@ Bool_t GeneratorHepMC::importParticles()
   }
 
   /** loop over particles **/
+  mParticles.clear();
   auto particles = mEvent->particles();
   for (int i = 0; i < particles.size(); ++i) {