How can i limit my Javascript code on my first page HTML?

Question

I've got a problem on my JAVASCRIPT code. I've make a first page with some products. I would make a link to my second page when i click on the product.

But on my second page, there is an error : "script.js:35 Uncaught (in promise) TypeError: Cannot read property 'appendChild' of null at getProducts (script.js:35)"

I don't understand what i have to do.

HTML index.html (page 1):

<section id="indexCam" class="container">
    <div class="row">
        <div id="colCam1" class="col-12 col-lg-4"></div>
        <div id="colCam2" class="col-12 col-lg-4"></div>
        <div id="colCam3" class="col-12 col-lg-4"></div>
    </div>
    <div class="row">
        <div id="colCam4" class="col-12 col-lg-4"></div>
        <div id="colCam5" class="col-12 col-lg-4"></div>
    </div>
</section>

HTML product.html (Page 2) :

<section class="container">
    <div class="row">
        <div class="col-12 col-lg-6 justify-content-center">
            <img id="pictureProduct" src="" alt="" />
        </div>
    </div>
    <div class="row">
        <div class="col-12 text-center">
            <h1>Produit :</h1>
            <p id="nameProduct"></p>
        </div>
    </div>
    <div class="row">
        <div class="col-12 text-center">
            <h2>Description :</h2>
            <p id="textProduct"></p>
        </div>
    </div>
    <div class="row">
        <div class="col-12 text-center">
            <h3>Choix de la lentille</h3>
        </div>
    </div>
    <div class="row">
        <div class="col-12 text-center">
            <h4>Prix :</h4>
            <p id="priceProduct"></p>
        </div>
    </div>
</section>

Javascript :

// Url produit
let urlProduct = "";

// Appel de produits index.html

const indexCam = document.getElementById("indexCam");

const colCam1 = document.getElementById("colCam1");
const colCam2 = document.getElementById("colCam2");
const colCam3 = document.getElementById("colCam3");
const colCam4 = document.getElementById("colCam4");
const colCam5 = document.getElementById("colCam5");

const cols = [colCam1, colCam2, colCam3, colCam4, colCam5];




const getProducts = async function() {
    let response = await fetch("http://localhost:3000/api/cameras" + urlProduct)
    let data = await response.json()
    console.log(data)
    for(i=0; i < data.length; i++) {
        let indexCard = document.createElement("div");
        let indexLink = document.createElement("a");
        let indexImg = document.createElement("img");
        let indexBodyCard = document.createElement("div");
        let indexProductTitle = document.createElement("h5");
        let indexProductPrice = document.createElement("p");
        
        cols[i].appendChild(indexCard);
        indexCard.classList.add("card");
        indexCard.appendChild(indexLink)
        indexLink.classList.add("stretched-link");
        indexLink.appendChild(indexImg);
        indexImg.classList.add("card-img-top");
        indexLink.appendChild(indexBodyCard);
        indexBodyCard.classList.add("card-body");
        indexBodyCard.appendChild(indexProductTitle)
        indexProductTitle.classList.add("card-title");
        indexBodyCard.appendChild(indexProductPrice);
        indexProductPrice.classList.add("card-text");
        
        indexProductTitle.innerHTML = data[i].name;
        indexProductPrice.innerHTML = parseInt(data[i].price / 100).toFixed(2) + " €";
        indexLink.setAttribute("href", "product.html?"+ data[i]._id)
        indexImg.setAttribute("src", data[i].imageUrl);
    }
}

getProducts()

// Page Produit

// Création de l'URL

function product() {
    if (document.getElementById("pictureProduct") != null) {
        let url = window.location.search
        const urlParams = new URLSearchParams(url)
        urlProduct = urlParams.get("id")

        document.getElementById("pictureProduct").setAttribute("src", data[i].imageUrl);
        document.getElementById("nameProduct").innerHTML = data[i].name;
        document.getElementById("textProduct").innerHTML = data[i].description;
        document.getElementById("priceProduct").innerHTML = parseInt(data[i].price / 100).toFixed(2) + "€";
    }
}

// Evenement on click

Error on the second page after click

Thanks for help

Nindra