Thread synchronization issue causing unexpected behavior

#include <iostream>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <queue>

std::mutex mtx;
std::condition_variable cv;
std::queue<int> q;
bool done = false;

void produce() {
    for (int i = 0; i < 10; ++i) {
        std::unique_lock<std::mutex> lock(mtx);
        q.push(i);
        std::cout << "Produced: " << i << std::endl;
        cv.notify_one();
    }
    done = true;
    cv.notify_one();
}

void consume() {
    std::unique_lock<std::mutex> lock(mtx);
    while (!done ||!q.empty()) {
        cv.wait(lock);
        if (!q.empty()) {
            std::cout << "Consumed: " << q.front() << std::endl;
            q.pop();
        }
    }
}

void produceConsume() {
    std::thread producer(produce);
    std::thread consumer(consume);
    producer.join();
    consumer.join();
}