Getting segmentation falut while using this STL?

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C++

STL

Hi friends, am getting core while dereference the list iterator. Hence, i required condition for not executing this lines. I have tried using list empty and size also. but it was no use of it.

#include<iostream>
#include<bits/stdc++.h>
using namespace std;

struct CtxThrottlingContainer
{
   string pci;
   string status;

   CtxThrottlingContainer()
   {
      pci = "";
      status = "";
   }
};

struct CtxThrottlingData
{
   map <int, list<CtxThrottlingContainer> > PendingThrottlingTriggerMap;
   map <string, string> m_ApplicableThrtlProfileMap;
};

map<string,CtxThrottlingData> g_SessionLvlThrottlingMap;

void New_Insertation()
{

   CtxThrottlingData ctx;
#if 0
   CtxThrottlingContainer c1;
   c1.pci = "pci";
   c1.status = "status";

   list<CtxThrottlingContainer> l1;
   l1.push_back(c1);
   ctx.PendingThrottlingTriggerMap.insert(make_pair(123, l1));
   ctx.m_ApplicableThrtlProfileMap.insert(make_pair("maths", "second"));
#endif

   g_SessionLvlThrottlingMap["total_key"] = ctx;
}

int main()
{
   map<string,CtxThrottlingData>::iterator itr = g_SessionLvlThrottlingMap.find("maths");
   if(itr == g_SessionLvlThrottlingMap.end())
   {
      New_Insertation();
   }

   itr = g_SessionLvlThrottlingMap.find("total_key");
   if(itr == g_SessionLvlThrottlingMap.end())
   {
      New_Insertation();
   }
   else
   {
      cout<<"g_SessionLvlThrottlingMap Key value is : "<<itr->first<<endl;

      map<int, list<CtxThrottlingContainer> > ::iterator itr2 = itr->second.PendingThrottlingTriggerMap.begin();
      list<CtxThrottlingContainer>::iterator it4 = itr2->second.begin();
      map <string, string> ::iterator itr3 = itr->second.m_ApplicableThrtlProfileMap.begin();

      cout<<"PendingThrottlingTriggerMap key is : "<<itr2->first<<endl;

      //if(it4 != itr2->second.end());
      if(itr2->second.empty())
      {
      if((it4->pci != "") && (it4->status != ""))
         {
            cout<<"PendingThrottlingTriggerMap list is : "<<it4->pci<<endl;
            cout<<"PendingThrottlingTriggerMap list is : "<<it4->status<<endl;
         }
      }

      itr3 = itr->second.m_ApplicableThrtlProfileMap.find("maths");
      if(itr3 != itr->second.m_ApplicableThrtlProfileMap.end())
      {
         cout<<"m_ApplicableThrtlProfileMap 1st : "<<itr3->first<<endl;
         cout<<"m_ApplicableThrtlProfileMap 2nd : "<<itr3->second<<endl;
      }
   }
}

What I have tried:

Tried list empty and list size but getting core dump continuously help me which is useful for proceed furthur.