replace "with" to use "if" block

Author: amarantha-k

src/partials/head-last.hbs

@@ -1,9 +1,9 @@
 <link rel="stylesheet" href="{{{uiRootPath}}}/css/site.css">
 <script src="{{{uiRootPath}}}/js/vendor/jquery.js"></script>
-{{#with env.OPTANON_SCRIPT_URL}}
-<script src="{{this}}" data-domain-script="{{env.OPTANON_SCRIPT_DATA_DOMAIN_SCRIPT}}"></script>
+{{#if env.OPTANON_SCRIPT_URL}}
+<script src="{{env.OPTANON_SCRIPT_URL}}" data-domain-script="{{env.OPTANON_SCRIPT_DATA_DOMAIN_SCRIPT}}"></script>
 <script>function OptanonWrapper(){}</script>
-{{/with}}
+{{/if}}
 {{#with site.keys.googleAnalytics}}
 <script>(window.dataLayer=window.dataLayer||[]).push({'gtm.start':+new Date(),event:'gtm.js'})</script>
 <script async src="https://www.googletagmanager.com/gtm.js?id={{{this}}}"></script>