Can Script - sprite swap

CanScript.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CanScript : MonoBehaviour
{

    public int dropsNum = 0;
    public GameObject water;
    bool warning = false;
    float warningTimer = 0;

    public List<Sprite> canSprites = new List<Sprite>();

    void Start()
    {
        water.transform.localScale = new Vector3(1, 0.25f * dropsNum, 1);
    }


    void Update()
    {
        //water.transform.localScale = new Vector3(1, 0.25f * dropsNum, 1);

        if (dropsNum < 4) GetComponent<SpriteRenderer>().sprite = canSprites[dropsNum];
        else warning = true;


        if (warning == true)
        {
            warningTimer += Time.deltaTime; //seconds
            if (warningTimer > 0) GetComponent<SpriteRenderer>().color = Color.red;
            if (warningTimer > 2) GetComponent<SpriteRenderer>().color = Color.yellow;
            if (warningTimer > 3)
            {
                GetComponent<SpriteRenderer>().color = Color.white;
                warning = false;
                warningTimer = 0;
                dropsNum = 0;
            }
        }

    }



}