title: SyntaxError: Unexpected token < in JSON at position 0 in Woocommerce Checkout page
body: <p>Today i noticed this strange error into <a href="http://moodmintdesign.com" rel="nofollow noreferrer">my Woocommerce site</a>. When try to checkout, fill all data, and press on Paypal button (I use Paypal as payment gateway), i get this error into top:</p>
  
  <pre><code>SyntaxError: Unexpected token &lt; in JSON at position 0
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/Wdf7J.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Wdf7J.png" alt="enter image description here"></a></p>
  
  <p>What i tryed to resolve:</p>
  
  <ol>
  <li>Disabled all plugins to identify conflict between -> No luck</li>
  <li><p>Tryed to check Inspect Element, and see this warning:</p>
  
  <p>Unable to fix malformed JSON checkout.min.js:1 </p></li>
  </ol>
  
  <p>Also checked error_log into my server, and there have this error:</p>
  
  <pre><code>[18-Apr-2018 17:04:17 UTC] PHP Fatal error:  Call to a member function get_order_number() on boolean in /home/moodmint/public_html/wp-content/plugins/woocommerce/includes/gateways/paypal/includes/class-wc-gateway-paypal-request.php on line 77
  </code></pre>
  
  <p>I use Woocommerce 3.3.5, and WooPress theme.</p>