PHP: $_GET

Please Enter Your Email and Password

The code used for index.php is below:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="../styles.css">
    <title>PHP: $_GET</title>
</head>
<body>
<h1 class="lesson-h1">PHP: $_GET</h1>
<h3>Please Enter Your Email and Password</h3>
<?php
    $email = htmlentities($_GET['email']);
    $password = htmlentities($_GET['password']);

  if(isset($_GET['email'])){
    get($email, $password);
    } 

function get($e, $p){
    if(!$e || !$p){
      echo "<script>window.alert('Error: Email and Password are Required');</script>";
    }
    else {
      echo "<p>Your Email Address is <strong>$e</strong> and Password is <strong>$p</strong></p>";
      echo "<p>GET Request Submitted: => Email: <strong>$e</strong> | Password: <strong>$p</strong></p>";  
    }
}
?>
<form action="index.php" method="GET">
    <label for="email">Email:
      <input type="email" name="email" placeholder="Email">
    </label>
    <label for="password">Password: 
      <input type="password" name="password" placeholder="Password">
    </label>
    <input type="submit" value="Submit">
</form>
<hr>
<?php
  include('../show_code.php');
  show_code('index.php');
?>
</body>
</html>