C++ Removing Unused Class Attribute Causes std::logic_error - c++

Question

I have a class which has a few attributes like shown below, my problem is that when I remove or place the string s attribute before std::atomic<char*> atomic_input the program terminates with exception:
'std::logic_error'
what(): basic_string::_M_construct null not valid
Aborted (core dumped)
#include <string>
#include <atomic>
// In ui.cpp
class UI
{
private:
std::atomic<char*> atomic_input;
std::string s; /* this can be renamed, but removing or placing it
before the above field crashes the program */
};
// In main.cpp
#include "ui.cpp"
int main()
{
srand (time(NULL));
initscr(); /* start the curses mode */
UI* ui = new UI();
return 0;
}
The string attribute is not accessed within the program in any way, renaming it is possible. The reason why I have an atomic field is that the value is shared among several threads.
I have tried placing the string field in different lines within the class attributes, the program only crashes if the declaration is before the atomic_input.
What might be causing the problem? Is it something to do with how the classes in C++ should be defined?

Answer 1

Looks like I've found a solution.
std::atomic<char*> atomic_input not being initialized like seen below was causing the issue. I still don't know how the string variable was interfering with it.
My guess is that the compiler somehow interprets the string as a constructor for atomic_input. The error only occurs when atomic_input is accessed in runtime and not in the compilation.
#include <string>
#include <atomic>
// In ui.cpp
class UI
{
private:
std::atomic<char*> atomic_input{(char*)""};
// std::string s; /* Initializing the atomic char like above solved the problem */
};