Blynk espnow watchdog problem help!

Hi I’m trying to implement ESP-NOW on 2 ESP8266 devices, I can send the data to turn on a led connected to (D1 in the receiver) but when I turn off the transmitter the receiver’s led is always on. How can I implement a watchdog ? example, if the data is not received, restart the system after a certain number of seconds.
Thank you

RECEIVER CODE :

#define D1 5
#include <ESP8266WiFi.h>
#include <espnow.h>
#include <SimpleTimer.h>
SimpleTimer timer;

int WatchdogLed = 0 ;
int count = 0;

typedef struct struct_message {
  int  WatchdogLed  ;
}
struct_message;
// Create a struct_message called myData
struct_message myData;

void onDataRecv(uint8_t * mac, uint8_t *incomingData, uint8_t len) {
  Serial.println("Messaggio ricevuto.");
  memcpy(&myData, incomingData, sizeof(myData));

}

void setup() {
  Serial.begin(115200);

  WiFi.mode(WIFI_STA);
  if (esp_now_init() != 0) {
    Serial.println("Problem during ESP-NOW init");
    return;
  }

  esp_now_set_self_role(ESP_NOW_ROLE_SLAVE);
  esp_now_register_recv_cb(onDataRecv);

  digitalWrite (D1, LOW);
  pinMode(D1, OUTPUT);
  timer.setInterval(1000L, myTimerEvent);
}

void myTimerEvent() {
  digitalWrite (D1, myData.WatchdogLed);

}

void loop() {
  timer.run ();
}

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