cJSON_Print return NULL  #45

Good afternoon.
I am using cJSON v1.7.12. I am trying to create a json of the form:
{ "status":"text", "num": 123 }

For this, I use the following code:
`
cJSON *monitor = cJSON_CreateObject();
if (monitor == NULL)
{
cJSON_Delete(monitor);
ESP_LOGE(TAG, "Error create json");
}
cJSON *status = cJSON_CreateString("text");

if (status == NULL)
{
cJSON_Delete(monitor);
ESP_LOGE(TAG, "Error create status");
}

cJSON_AddItemToObject(monitor, "status", status);
int k = 123;
cJSON *num = cJSON_CreateNumber(k);
ESP_LOGI(TAG, "End cJSON_CreateNumber");
if (num == NULL)
{
    cJSON_Delete(monitor);
    ESP_LOGE(TAG, "Error create num");
}

cJSON_AddItemToObject(monitor, "num", num);
ESP_LOGI(TAG, "End cJSON_AddItemToObject");
char* resp_str = cJSON_PrintUnformatted(monitor);
ESP_LOGI(TAG, "End cJSON_Print");
ESP_LOGI(TAG, "out_json: \n '%s'", resp_str);

`

I found that if cJSON_CreateNumber is in my code, then the cJSON_Print function returns null. What is the reason for this problem?