fixed errors

src/HEP/Geant/ActionInitialization.cpp

@@ -12,6 +12,15 @@ ActionInitialization::ActionInitialization(EmitterPrimary *emitter, SimulationCo
 {}
 
 ActionInitialization::~ActionInitialization() {}
+  
+// Lightweight wrapper to avoid double-free in Geant4 EventManager
+class SteppingActionWrapper : public G4UserSteppingAction {
+public:
+  SteppingActionWrapper(SteppingAction *real) : m_Real(real) {}
+  virtual void UserSteppingAction(const G4Step* step) override { m_Real->UserSteppingAction(step); }
+private:
+  SteppingAction *m_Real;
+};
 
 void ActionInitialization::BuildForMaster() const {}
 
@@ -21,10 +30,12 @@ void ActionInitialization::Build() const {
   } else {
     SetUserAction(new EmitterPrimary());
   }
-
+  
   SteppingAction *sa = new SteppingAction(m_Context);
-  SetUserAction(static_cast<G4UserSteppingAction*>(sa));
+  // EventManager will delete sa via this slot
   SetUserAction(static_cast<G4UserEventAction*>(sa));
+  // EventManager will delete the wrapper, leaving sa alive to be deleted once.
+  SetUserAction(new SteppingActionWrapper(sa));
 }
 
 } // namespace Geant