SPI connection error

Question

when I use following code for SPI connection I will be notice this error

what is the matter?

#include <zephyr/kernel.h>
#include <zephyr/drivers/spi.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/sys/printk.h>

/* 1000 msec = 1 sec */
#define SLEEP_TIME_MS   1000

#define LED1_NODE DT_ALIAS(led1)
static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(LED1_NODE, gpios);

static const struct spi_config spi_cfg = {


.operation = SPI_WORD_SET(8),


.frequency = 4000000,
.slave = 0,
};

struct device * spi_dev;

static void spi_init(void)
{
const char* const spiName = "SPI_0";
spi_dev = device_get_binding(spiName);

if (spi_dev == NULL) {
    printk("Could not get %s device\n", spiName);
    return;
}
}

void spi_test_send(void)
{
int err;
static uint8_t tx_buffer[1];
static uint8_t rx_buffer[1];

const struct spi_buf tx_buf = {
    .buf = tx_buffer,
    .len = sizeof(tx_buffer)
};
const struct spi_buf_set tx = {
    .buffers = &tx_buf,
    .count = 1
};

struct spi_buf rx_buf = {
    .buf = rx_buffer,
    .len = sizeof(rx_buffer),
};
const struct spi_buf_set rx = {
    .buffers = &rx_buf,
    .count = 1
};

err = spi_transceive(spi_dev, &spi_cfg, &tx, &rx);
if (err) {
    printk("SPI error: %d\n", err);
} else {
    /* Connect MISO to MOSI for loopback */
    printk("TX sent: %x\n", tx_buffer[0]);
    printk("RX recv: %x\n", rx_buffer[0]);
    tx_buffer[0]++;
}
}

void main(void)
{
printk("SPIM Example\n");
spi_init();

while (1) {
    spi_test_send();
    k_sleep(K_MSEC(1000));
}
}