if(isset($_POST['login'])) {
    require 'connect.php';

    $email = $_POST['email'];
    $password = $_POST['password'];
    $select_userdata = "select * from users where password ='$password' AND email = '$email'";

    $run_check = mysqli_query($dbconfig, $select_userdata);
    $check_user = mysqli_num_rows($run_check);

    /**Error part**/
    if ($check_user == 0) {
        echo "<script>alert('Password or email is incorrect')</script>";
        echo "<script>window.open('login.php','_self')</script>";
    }
    $_SESSION['email'] = $email;
    echo "<script>alert ('You Have Been Logged in')</script>";
    header('Location: index.php');
    exit;

}
if(isset($_GET['logout'])) {
    unset($_SESSION['email']);
}