Which potential concurrency issue is demonstrated by the execution of the following code snippet?

import java.util.ArrayList;

public class ExceptionThread {
    static ArrayList<Integer> list = new ArrayList<>();
    public static void main(String[] args) {
        list.add(1);
        list.add(2);
        Thread t = new Thread(() -> {
            try {
                list.remove(0);
            } catch(Exception e) {
                System.out.println("Error");
            }
        });
        t.start();
        // Main thread iterates concurrently without synchronization
        for (Integer i : list) {
            System.out.println(i);
        }
    }
}