What causes the stored std::list::iterator to become invalid?

edit: The below code can be run on https://wandbox.org/permlink/1Qry83quzoDveYDi
I implemented various suggestions from the comments, but unfortunately, it is still not clear to my why erasing the item at this particularstd::list::iterator (line 86) crashes at runtime. All the explanations given below seem to affirm that the iterator should still be valid at this point.

I was under the impression that iterators to items in a std::list do not get invalidated when an item is inserted into a list (refer to this excellent post).

However, in the below code, the line
items.at(noOfitems-2)->erase(iter++); (line 86)
crashes the program with
malloc: *** error for object 0x100778b28: pointer being freed was not allocated.

Could you please help me understand why (where) this iterator std::list<std::string>::iterator becomes invalid, and how I can make it work without iteratively finding it again?

Am I perhaps misunderstanding the error?

#include <iostream>#include <iostream>#include <vector>#include <random>#include <unordered_set>#include <set>#include <unordered_map>#include <map>#include <list>#include <utility>#include <chrono>#include <sstream>#include <tr1/memory>class Increment;struct Item;struct Pairhash {public:  template <typename T>  std::size_t operator()(const T &x) const  {      return std::hash<T>()(x) ^ std::hash<T>()(x);  }};struct Item {    Item() = default;    std::string name;    int counter;    Item(std::string name) : counter(0)    {        this->name = name;    }    bool operator==(const Item& p) const    {        return (this->name == p.name);    }    bool operator<(const Item& p) const    {        return (this->counter < p.counter);    }};class Increment {private:    std::unordered_map<std::string, std::pair<std::list<std::string>::iterator , std::shared_ptr<Item> >, Pairhash >  itemMap;    std::vector<std::shared_ptr<std::list<std::string>>> items;public:    Increment() = default;    std::list<std::string>::iterator insertItem(std::string & name , int noOfitems)    {        if (noOfitems > items.size())        {            items.emplace_back(std::make_shared<std::list<std::string>>(std::initializer_list<std::string>{ name }));            return items.back()->begin();        }        else        {            items.at(noOfitems-1)->emplace_back(name);            return items.at(noOfitems-1)->rbegin().base(); //Last position in list        }    }    std::list<std::string>::iterator adjustItemPosition(std::string & name, int noOfitems, std::list<std::string>::iterator & iter)    {        if (noOfitems > items.size())        {            std::list<std::string> temp{name};            items.push_back(std::make_shared<std::list<std::string>>(temp));        }        else        {            items.at(noOfitems-1)->emplace_back(name);        }        /* // Works as expected        auto itr = std::find(items.at(noOfitems-2)->begin(), items.at(noOfitems-2)->end(), name);        if (itr != items.at(noOfitems-2)->end())        {            items.at(noOfitems-2)->erase(itr);        }        */        items.at(noOfitems-2)->erase(iter++); //TODO Crashes        return items.at(noOfitems-1)->rbegin().base(); //Last position in list    }    void incrementByOne(std::string name)    {        auto it = itemMap.find(name);        if (it != itemMap.end()) //Item already in map        {            it->second.second->counter++;            it->second.first = adjustItemPosition(name, it->second.second->counter,                                                    it->second.first);        }        else  //New item to be inserted        {            std::shared_ptr<Item> temp = std::make_shared<Item>(Item(name));            temp->counter = 1;            std::list<std::string>::iterator listIter = insertItem(name, 1);            itemMap.emplace(name, std::make_pair( listIter, temp));        }    }    std::string printTop10() const    {        std::stringstream ss;        auto count(0);        for (auto it = items.rbegin(); it != items.rend(); ++it)        {            for (auto item : **it)            {                if (count == 10)                {                    break;                }                ss << "We have " << itemMap.at(item).second->counter << " " << item << std::endl;++count;            }        }        return ss.str();    }};int main(int argc, const char * argv[]) {    Increment incrementer;    std::vector<std::string> names{ "Bananas", "Apples", "Peaches", "Durians", "Hazelnuts", "Avocados", "Pineapples", "Cherries", "Almonds", "Olives", "Eggs", "Yoghurts", "Peas", "Blueberries" };    for (int i = 0; i < 100; ++i) {        incrementer.incrementByOne(names.at(i%10));    }    std::cout << incrementer.printTop10() << std::endl;    return 0;}