Arduino Advanced Lightning detector with AS3935 lightning sensor (code)

#include <Wire.h>
#include <LiquidCrystal.h>
#include "PWFusion_AS3935_I2C.h"

// ---------------- BUTTONS ----------------
#define RECALL_BTN_PIN   A0
#define CLOSEST_BTN_PIN  A1

// ---------------- LCD ----------------
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 8;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

// ---------------- AS3935 ----------------
#define IRQ_PIN 2
#define SI_PIN  9
#define AS3935_ADD 0x03
#define AS3935_CAPACITANCE 80

#define AS3935_INDOORS 1
#define AS3935_DIST_EN 1

PWF_AS3935_I2C lightning0(IRQ_PIN, SI_PIN, AS3935_ADD);

// ---------------- LEDS ----------------
#define YELLOW_LED_PIN 6
#define RED_LED_PIN    7

#define KM_15_MILES 24
#define KM_35_MILES 56

// ---------------- STATE ----------------
volatile bool AS3935_ISR_Trig = false;

float lastStrikeMiles = -1.0;
float closestStrikeMiles = 9999.0;

unsigned long ledOffTime = 0;
unsigned long lcdMessageUntil = 0;
bool showingMessage = false;

// ---------------- ISR ----------------
void AS3935_ISR() {
  AS3935_ISR_Trig = true;
}

// ---------------- SETUP ----------------
void setup() {
  Serial.begin(115200);
  Wire.begin();

  pinMode(RECALL_BTN_PIN, INPUT_PULLUP);
  pinMode(CLOSEST_BTN_PIN, INPUT_PULLUP);

  pinMode(YELLOW_LED_PIN, OUTPUT);
  pinMode(RED_LED_PIN, OUTPUT);

  lcd.begin(16, 2);
  lcd.print("Lightning Det.");
  lcd.setCursor(0, 1);
  lcd.print("Initializing");
  digitalWrite(YELLOW_LED_PIN, LOW);
  digitalWrite(RED_LED_PIN, LOW);
  delay(1000);
  digitalWrite(YELLOW_LED_PIN, HIGH);
  digitalWrite(RED_LED_PIN, HIGH);


  delay(1500);

  lightning0.AS3935_DefInit();
  lightning0.AS3935_ManualCal(
    AS3935_CAPACITANCE,
    AS3935_INDOORS,
    AS3935_DIST_EN
  );

  attachInterrupt(digitalPinToInterrupt(IRQ_PIN), AS3935_ISR, RISING);

  lcd.clear();
  lcd.print("Listening...");
  Serial.println("Listening...");
}

// ---------------- LOOP ----------------
void loop() {
  unsigned long now = millis();

  // ---- LCD AUTO RETURN ----
  if (showingMessage && now > lcdMessageUntil) {
    lcd.clear();
    lcd.print("Listening...");
    showingMessage = false;
  }

  // ---- BUTTON: LAST STRIKE ----
  if (!digitalRead(RECALL_BTN_PIN)) {
    lcd.clear();
    lcd.print("Last Strike:");
    lcd.setCursor(0, 1);
    if (lastStrikeMiles < 0)
      lcd.print("No data");
    else {
      lcd.print(lastStrikeMiles, 1);
      lcd.print(" mi");
    }
    lcdMessageUntil = now + 2000;
    showingMessage = true;
  }

  // ---- BUTTON: CLOSEST ----
  if (!digitalRead(CLOSEST_BTN_PIN)) {
    lcd.clear();
    lcd.print("Closest Strike:");
    lcd.setCursor(0, 1);
    if (closestStrikeMiles > 9000)
      lcd.print("No data");
    else {
      lcd.print(closestStrikeMiles, 1);
      lcd.print(" mi");
    }
    lcdMessageUntil = now + 2000;
    showingMessage = true;
  }

// ---- AS3935 EVENT ----
if (AS3935_ISR_Trig) {
  AS3935_ISR_Trig = false;

  uint8_t src = lightning0.AS3935_GetInterruptSrc();
  float miles = -1.0;   // <-- DECLARED HERE (fix)

  if (src == 1) {
    uint8_t km = lightning0.AS3935_GetLightningDistKm();
    miles = km * 0.621371;

    lastStrikeMiles = miles;
    if (miles < closestStrikeMiles)
      closestStrikeMiles = miles;

    lcd.clear();
    lcd.print("STRIKE!");
    lcd.setCursor(0, 1);
    lcd.print(miles, 1);
    lcd.print(" mi");

    showingMessage = true;
    lcdMessageUntil = now + 3000;

    // LED logic
    if (km <= KM_15_MILES) {
      digitalWrite(RED_LED_PIN, LOW);
      delay(800);
      digitalWrite(RED_LED_PIN, HIGH);
    }
    else if (km <= KM_35_MILES) {
      digitalWrite(YELLOW_LED_PIN, LOW);
      delay(800);
      digitalWrite(YELLOW_LED_PIN, HIGH);
    }

    ledOffTime = now + 1500;

    Serial.print("Lightning: ");
    Serial.print(miles);
    Serial.println(" mi");
  }
  else if (src == 2) {
    Serial.println("Disturber detected");
  }
  else if (src == 3) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Interference");
    lcd.setCursor(0, 1);
    lcd.print("Move sensor");

    Serial.println("Noise level too high");

    showingMessage = true;
    lcdMessageUntil = now + 2000;
  }
 }
}