PHP does nothing if username/email is wrong - php

Question

I'm making a login system. Everything works, but when i use a email (username) in the login that is not in the database it will go to the URL with filename and then just the form data (email and password). I need to set the header with an error so i can say that login was failed. Does anyone see the problem?
<?php
ob_start();
if (isset($_REQUEST['password'])) {
require 'connect.php';
$password = $_REQUEST['password'];
$mail = $_REQUEST['email'];
if (empty($mail) || empty($password)) {
header('location: ../login.php?error=empty');
exit();
} else {
$sql = "SELECT * FROM account WHERE email = ?;";
$stmt = mysqli_stmt_init($connect);
if (!mysqli_stmt_prepare($stmt, $sql)) {
header("Location: ../login.php?error=sqlError");
exit();
} else {
mysqli_stmt_bind_param($stmt, "s", $mail);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);
if ($row = mysqli_fetch_assoc($result)) {
$passwordCheck = password_verify($password, $row['wachtwoord']);
if ($passwordCheck == false) {
header("Location: ../login.php?error=passwordWrong");
exit();
} elseif ($passwordCheck == true) {
session_start();
$_SESSION['userId'] = $row['account_id'];
$_SESSION['username'] = $row['gebruikersnaam'];
header("Location: ../index.php?login=succes");
exit();
}
} else {
header("Location login.php?error=noUser");
exit();
}
}
}
} else {
header("Location: ../login.php?error=");
exit();
}

Answer 1

Since your login form is working.
Let me ask you:
Is Your form action using get method or post method?.
Remember when you send a form with GET method to backend eg to a php file, all the form parameters are seen in the url okay.
So You can check this below.
1.) Ensure that your form is using Post method eg method="POST"
2). Why are you using $_REQUEST[..]. in php
its better you used $_POST method for http request coming from form inputs
Something like
if(isset($_POST['submit'])){
require 'connect.php';
$password = $_POST['password'];
$mail = $_POST['email'];
OR
if (isset($_POST['password'])) {
require 'connect.php';
$password = $_POST['password'];
$mail = $_POST['email'];
Note: The variables in $_REQUEST are provided to the script via the GET, POST, and COOKIE input mechanisms and
therefore could be modified by the remote user and cannot be trusted. Therefore proper validation and sanitization should be
done on both front and backend.
see php manual warnings
Finally,
If any of this suggestion does not work for you, you can then upload also all your form fields and I will get it working for you. Thank You