Issue trying to get Facebook SDK to work in Wordpress template file

Hello,
I'm creating a custom template file for my Avada child theme. I'm using the Facebook SDK and would eventually like to create a box where people can send messages straight through to Facebook.

I have created the following custom template file:

<?php
/*
Template Name: Isary Contact Page
*/
?>

<?php get_header();

?>

 
<script>
  window.fbAsyncInit = function() {
    FB.init({
      appId      : '1366583986735816',
      xfbml      : true,
      version    : 'v2.9'
    });
    FB.AppEvents.logPageView();
  };

  (function(d, s, id){
     var js, fjs = d.getElementsByTagName(s)[0];
     if (d.getElementById(id)) {return;}
     js = d.createElement(s); js.id = id;
     js.src = "//connect.facebook.net/en_US/sdk.js";
     fjs.parentNode.insertBefore(js, fjs);
   }(document, 'script', 'facebook-jssdk'));
</script>

<div
  class="fb-like"
  data-share="true"
  data-width="450"
  data-show-faces="true">
</div>

<?php do_action( 'avada_after_content' ); ?>
<?php get_footer();

Code (markup):

When I do this, I get the following error in Console:

If I remove the get_header() section, part of the Avada theme wont load, and I get the following error:

I've been scratching my head at this for the last few hours. Any help is greatly appreciated.

Best wishes,

Graeme