Why do i still get Undefined array key errors if i did everything correctly? [duplicate]

I tried putting “isset()”, i tried putting null, i researched every single solution and NOTHING works.

It says that:
Warning: Undefined array key “GoogleMaps” in C:xampphtdocspaonlineconfig_novapadeiras.php on line 11

For context: My idea is that you are suppost to be able to send a full link from any bakery from Google Maps, but that is what is giving me problems.

This is my code on php :

<?php

if ($_SERVER['REQUEST_METHOD'] == 'POST' && isset($_POST['enviar'])) {

  $conn= mysqli_connect('localhost', 'root', '', 'paonline') or die("Falho de connexao:" .mysqli_connect_error());
  
  if(isset($nome) && isset($localidade) && isset($padeiramap));

$nome =       $_POST['nome'];
$localidade = $_POST['localidade'];
$padeiramap = $_POST['GoogleMaps'];

return $GoogleMaps[$padeiramap] ?? null;

$sql= "INSERT INTO 'padeiras' ('nome','localidade','GoogleMaps') VALUES ('$nome','$localidade','$padeiramap')";

$query = mysqli_query($conn,$sql);
if($query) {
    echo "Dados enviados! Agora o nosso equipo revisara se a sua padeira tem todo o preciso para ser colocada em nossa web.";
}
else {
    echo "Aconteceu um erro! Revise se tem introducido bem os dados na sua padeira ou espere um tempo e volte a temtar registrar a sua padeira.";
}

}

?>

and this is my code in the html form:

<fieldset>
    <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method='POST'>
            <div class="form-group">
                <center><label>Nome da padeira</label></center>
                <center><input type="text" name="nome" id="nome" required></center>
            </div>    
            <div class="form-group">
                <center><label>Localidade</label></center>
                <center><input type="radio" name="localidade" value="Murtosa" required>Murtosa</center>
                <center><input type="radio" name="localidade" value="Estarreja" required>Estarreja</center>
                <center><input type="radio" name="localidade" value="Ovar" required>Ovar</center>
            </div>
            <div class="form-group">
                <center><label>Link no Google Maps:</label></center>
                <center><input type="url" name="padeiramap" id="padeiramap" required></center>
            </div>  
            <center><div class="form-group">
                <input type="submit" id="Enviar" name="enviar">
                <input type="reset" id="Reiniciar" name="reiniciar">
            </div></center>
        </form>
 </fieldset>

</body>
</html>

This are two separated files on the same folder by the way.

And please, before you ask:

• NO, i do not know what do you mean with having “MySQL installed”. If you are talking about hacing Apache and MySQL started in XAMPP them yes, i have them both.
• YES, i have removed the $bd and $link connections so it not longers causes conflict.
• NO, I do not know what do you mean with my code been vulnerable to SQL injections, is not suppost to be a public web.
• Avoid downvoting my question. I am asking for help with something very important for me and i would not like it if i got spitted on my face.