index error ish

<?php
include 'resource/session.php';
include 'resource/database.php';
include 'resource/utlities.php';

if (isset($_POST['loginBtn'])){
    $form_errors = array();
//validate
    $required_fields = array('username', 'password');
    $form_errors = array_merge($form_errors, check_empty_fields($required_fields));
    if (empty($form_errors)){
        //check user exist
        //collect data
        $user = $_POST['username'];
        $password = $_POST['password'];
        $sqlQuery = "SELECT * FROM my_db user2 WHERE username = :username";
        $statement = $db->prepare($sqlQuery);
        $statement->execute(array(':username'=> $user));

        while($row = $statement->fetch()){
            $id = $row['id'];
            $hashed_password = $row['password'];
            $username = $row['username'];

            if (password_verify($password, $hashed_password)){
                $_SESSION['id'] = $id;
                $_SESSION['username'] = $username;
                header('Location: index.php');
            }else{
                $result = "<p style='padding: 20px; color: red; border: 1px solid gray;'>Invalid username or password</p>";
            }
        }

    }else{
        if(count($form_errors) == 1){
            $result = "<p style='color:red;'>There was 1 error in the form</p>";
        }else{
            $result = "<p style='color:red;'>There were ".count($form_errors)." errors in the form</p>";
        }
    }


}


?>


<!DOCTYPE html>
<html>
<head lang = "en">
<meta charset = "UTF-8">
<title>Loginpage</title>
</head>
<body>


<h2>User Authentication System</h2><br>


</body>


<h3>login Form</h3>

<?php
if (isset($result)) echo $result;

?>
<?php

if (!empty($form_errors))
    echo show_errors($form_errors);


?>

<form method = "post" action = "">
    <table>
        <tr>
            <td>Username: </td>
            <td><input type = "text" value = "" name="username"></td>
        </tr>
        <tr>
            <td>Password: </td>
            <td><input type = "password" value = "" name="password"></td>
        </tr>
        <tr><td></td><td><input style = "float:right;" type = "submit" name="loginBtn" value = "Signin"></td></tr>
    </table>
</form>

<p><a href = "index.php">Back</a></p>


</html>