尝试合并类的排序数组时出现空指针异常

public class MergeSortedArrays {
    public static int[] merge(int[] arr1, int[] arr2) {
        // 检查数组是否为null
        if (arr1 == null && arr2 == null) {
            return null;
        }
        if (arr1 == null) {
            return arr2;
        }
        if (arr2 == null) {
            return arr1;
        }

        int n1 = arr1.length;
        int n2 = arr2.length;
        int[] mergedArray = new int[n1 + n2];
        int i = 0, j = 0, k = 0;

        // 合并两个数组
        while (i < n1 && j < n2) {
            if (arr1[i] <= arr2[j]) {
                mergedArray[k++] = arr1[i++];
            } else {
                mergedArray[k++] = arr2[j++];
            }
        }

        // 处理剩余元素
        while (i < n1) {
            mergedArray[k++] = arr1[i++];
        }
        while (j < n2) {
            mergedArray[k++] = arr2[j++];
        }

        return mergedArray;
    }

    public static void main(String[] args) {
        int[] arr1 = {1, 3, 5};
        int[] arr2 = {2, 4, 6};
        int[] merged = merge(arr1, arr2);
        if (merged != null) {
            for (int num : merged) {
                System.out.print(num + " ");
            }
        } else {
            System.out.println("Merged array is null");
        }
    }
}