Why do i get "Cannot open file: /src/gcc-5.1.0/libgcc/unwind-seh.c" when std::length_error is thrown?

Why do i get "Cannot open file: /src/gcc-5.1.0/libgcc/unwind-seh.c" when std::length_error is thrown? Here is code:

void User_Account::set_username(string name)
{
    if(!is_valid(name))throw length_error("Length has to be greater than 8");
    username =name;
}
void User_Account::set_password(string pass)
{
    pwd = pass;
}


//helper functions
bool is_valid(const string& s)
{
      const string::size_type acceptable_size = 8;
      return s.size() >= acceptable_size;
}

main:

try
{
    newuser.set_password(password);
    newuser.set_username(username);
}
catch(const length_error& e)
{
    cerr<<e.what();
}