std::string::erase() segfaults when given an iterator - c++11

Question

I have a string-
std::string out;
and an iterator over that string-
std::string::iterator pos = out.begin();
if I do -
if(!out.empty() || pos > out.begin())
out.erase(pos--);
It segfaults, with this error-
Program received signal SIGSEGV, Segmentation fault.
__memmove_ssse3 () at ../sysdeps/x86_64/multiarch/memcpy-ssse3.S:2821
2821 ../sysdeps/x86_64/multiarch/memcpy-ssse3.S: No such file or directory.
What am I missing?
For some context, I'm implementing line editing with ncurses and this code defines behaviour when backspace is pressed.
EDIT
It segfaults even after I move the decrement out of the call.
here is an MCVE -
#include <string>
#include <ncurses.h>
int main()
{
initscr();
cbreak();
keypad(stdscr, true); //Seems to be causing the error
std::string out;
std::string::iterator pos = out.begin();
short ch;
bool insert = false;
int y, x;
while(true)
{
ch = getch(); //Get next character
if(ch == '\n')
break; //End of line
else if(ch == KEY_BACKSPACE) //Backspace behaviour defined here
{
if(!out.empty())
{
out.erase(pos); //Character erased from string as per backspace
addch('\b'); //Erasure reflected on screen
std::string temp(pos, out.end()); //
getyx(stdscr, y, x);
mvaddstr(y, x - 1, temp.c_str());
}
}
else if(std::isalnum(ch) || std::ispunct(ch)) //Normal characters
{
if(!insert) //If insert is off
out.insert(pos++, ch); //Character inserted normally
else //Insert is on
{
*pos = ch; //Overwrite characters
pos++;
}
}
}
endwin();
return 0;
}
Compile with
g++ -lncurses -std=c++11
-Wall gives no clues.

Answer 1

This is expected behaviour for std::string. In the C++ standard, validity of string iterators is not garanteed after a modification of the string, contrary to other types with stronger requirements.
In [string.require] (§21.4.1), the standard states:
References, pointers, and iterators referring to the elements of a
basic_­string sequence may be invalidated by the following uses of
that basic_­string object: [...] Calling non-const member functions,
except operator[], at, data, front, back, begin, rbegin, end, and
rend.