"Abort trap" error in c++

I have an array of size 8, and I send only the second half of the array to my insertion sort. It successfully sorts only the second half of the array, but there is a statement at the bottom, "Abort trap: 6". Below are my main.cc and my insertionSort.cc files. What is causing the "Abort trap: 6" error?


Here is the output:
Before sorting
9 8 10 2 4 6 50 1
After sorting
9 8 10 2 1 4 6 50
Abort trap: 6


main.cc

Code:

---

#include <cstdio>
#include "insertionSort.h"

int main() {

    // create array
    int array[] = {9, 8, 10, 2, 4, 6, 50, 1};

    // get size of the array
    int size = sizeof(array) / sizeof(array[0]);

    // display array before reversing
    printf("Before sorting\n");
    for (int i = 0; i < size; i++) {
        printf("%d ", array[i]);
    }

    // new line
    printf("\n");

    // sort only the second half of the array
    insertionSort(array+(size/2), size);

    // display the array again after reversing
    printf("After sorting\n");
    for (int i = 0;i < size; i++) {
        printf("%d ", array[i]);

    } // end of for loop

    // new line
    printf("\n");
 
} // end of main

---

insertionSort.cc

Code:

---

#include "insertionSort.h"

void insertionSort(int* array, int size) {

    for (int i = 1; i < size; i++) {
        int key = array[i];
        int j = i - 1;

        while (j >= 0 && array[j] > key) {
            array[j+1] = array[j];
            j--;
        } // end of while loop

        // swap
        array[j+1] = key;

        } // end of for loop

} // end of insertionSort

---

Code:

---

    insertionSort(array+(size/2), size);

---

The second argument is the number of elements to sort. In this case the size of the passed array should be 4 not 8 as you are only sorting the second half of the array.

thanks