TileSimAlgs: Fix merging Tile E1 and MBTS cells (ATLASSIM-6580)

Tile Hit vector to container tool has been updated to fix merging hits corresponding to some E1 and MBTS cells (which are really merged in used geometry).

Firstly, old hits are removed using the corresponding collection iterators and only then new ones (merged) are added to the collection if it is needed, since addition of new hits to the same collection can invalidate the iterators.

TileCalorimeter/TileSimAlgs/src/TileHitVecToCntTool.cxx

 /*
-  Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
 */
 
 //************************************************************
@@ -1137,11 +1137,12 @@ void TileHitVecToCntTool::findAndMergeE1(TileHitCollection* coll, int frag_id, T
   if (fromHitIt != coll->end()) {
     ATH_MSG_VERBOSE("Found TileHit (E1 cell) for merging [" << m_tileID->to_string((*fromHitIt)->pmt_ID(), -1) 
 		    << "] in module: " << module);
+    bool isToHitNew = false;
     if (toHit == 0) {
       int side = m_tileID->side((*fromHitIt)->pmt_ID());
       Identifier to_pmt_id = m_tileID->pmt_id(TileID::GAPDET, side, module, E1_TOWER, TileID::SAMP_E, 0);
       toHit = new TileHit(to_pmt_id);
-      hitCont->push_back(toHit);
+      isToHitNew = true;
       ATH_MSG_VERBOSE("New TileHit (E1 cell) for merging added Id: " << m_tileID->to_string(toHit->pmt_ID(), -1) );
     } else {
       ATH_MSG_VERBOSE("Found TileHit (E1 cell) for merging Id: " << m_tileID->to_string(toHit->pmt_ID(), -1) );
@@ -1163,6 +1164,10 @@ void TileHitVecToCntTool::findAndMergeE1(TileHitCollection* coll, int frag_id, T
     }
     
     coll->erase(fromHitIt);
+
+    if (isToHitNew) {
+      hitCont->push_back(toHit);
+    }
   }
 }
 
@@ -1190,12 +1195,13 @@ void TileHitVecToCntTool::findAndMergeMBTS(TileHitCollection* coll, int frag_id,
   if (fromHitIt != coll->end()) {
     ATH_MSG_VERBOSE("Found TileHit (MBTS) for merging [" << m_tileTBID->to_string((*fromHitIt)->pmt_ID(), 0) 
 		    << "] in module: " << module);
+    bool isToHitNew = false;
     if (toHit == 0) {
       int side = m_tileTBID->side((*fromHitIt)->pmt_ID());
       int phi = m_tileTBID->phi((*fromHitIt)->pmt_ID()) - 1;
       Identifier to_pmt_id = m_tileTBID->channel_id(side, phi, 1);
       toHit = new TileHit(to_pmt_id);
-      hitCont->push_back(toHit);
+      isToHitNew = true;
       ATH_MSG_VERBOSE("New TileHit (MBTS) for merging added Id: " << m_tileTBID->to_string(toHit->pmt_ID(), 0) );
     } else {
       ATH_MSG_VERBOSE("Found TileHit (MBTS) for merging Id: " << m_tileTBID->to_string(toHit->pmt_ID(), 0) );
@@ -1218,6 +1224,9 @@ void TileHitVecToCntTool::findAndMergeMBTS(TileHitCollection* coll, int frag_id,
     }
     
     coll->erase(fromHitIt);
-  }
 
+    if (isToHitNew) {
+      hitCont->push_back(toHit);
+    }
+  }
 }