Merge branch 'master' of github.com:talview/proview-moodle

frame.php

@@ -77,13 +77,14 @@ function receiveMessage(event) {
 
     // Javascript event listener for window post message API (Ref: https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage)
     window.addEventListener("message", receiveMessage, false);
+    window.addEventListener('error', function(e) {
+      document.getElementById('contentIFrame').src = 'https://pages.talview.com/proview/error/index.html';//setting error page when error occured.
+    }, true);
 
 
     //Javascript function to start proview invoked upon postmessage from iframe
     function startProview(authToken, session, proview_url, clear, skipHardwareTest, previewStyle) {
       let url = proview_url || '//cdn.proview.io/init.js';
-      //Setting src attribute as error page URL so if the proview is not loaded error page will be shown
-      document.getElementById('contentIFrame').src = 'https://pages.talview.com/proview/error/index.html';
       let iframeWindow = document.getElementById('contentIFrame').contentWindow;
       (function(i,s,o,g,r,a,m){i['TalviewProctor']=r;i[r]=i[r]||function(){
         (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),