if-statement not working with creating and object

working on a project to create a website to buy tickects, and on the site you need to fill in every box for the code to create an object and store that in an array if not filled inn it will clear all the input boxes and show an error message. but even with some of the requirements failing it still pushes to the array.

JS code: '''

const billett = [];
function test() {


    let valgtFilm = document.getElementById("film").value;
    let antall = document.getElementById("antall").value;
    let fornavn = document.getElementById("forNavn").value;
    let etternavn = document.getElementById("etterNavn").value;
    let telefon = document.getElementById("telefornr").value;
    let epost = document.getElementById("epost").value;
    let tall = Number(antall);
    let telefonnr = Number(telefon);

    let ut = "<table><tr>" +
        "<th>Film</th><th>antall</th><th>Navn</th><th>Etternavn</th><th>Telefonnr</th><th>Epost</th>" +
        "</tr>";

    const nyBillett = {
        film: valgtFilm,
        antall: tall,
        navn: fornavn,
        etternavn: etternavn,
        tlf: telefonnr,
        epost: epost,
    }

    if (valgtFilm === "non") {
        document.getElementById("valgterr").innerHTML = "Velg en film";

    }
    if (tall <= 0) {
        document.getElementById("antallerr").innerHTML = "Skriv inn antall biletter";
    }
    if (fornavn === "") {
        document.getElementById("forNavnerr").innerHTML = "Skriv inn fornavnet ditt";
    }
    if (etternavn === "") {
        document.getElementById("etterNavnerr").innerHTML = "Skriv inn etternavnet ditt";
    }
    if (isNaN(telefonnr) || telefon === "") {
        document.getElementById("tlferr").innerHTML = "Skriv inn telefon nummeret ditt";
    }
    if (epost === "") {
        document.getElementById("eposterr").innerHTML = "Skriv inn en epost";
    }
    else {

        billett.push(nyBillett);
        for (let b of billett){

            ut += "<tr>";
            ut += "<td>" + b.film + "</td><td>" + b.antall + "</td><td>" + b.navn + "</td><td>" + b.etternavn + "</td><td>" + b.tlf + "</td><td>" + b.epost + "</td>";
            ut += "</tr>";

            document.getElementById("bestilt").innerHTML = ut;

            //fjerner verdier
            document.getElementById("film").value = 'Velg film her';
            document.getElementById("antall").value = "";
            document.getElementById("forNavn").value = "";
            document.getElementById("etterNavn").value = "";
            document.getElementById("telefornr").value = "";
            document.getElementById("epost").value = "";
        }
    }
}

'''