IdentityLink check ats after delaySync (prebid#5070)

modules/identityLinkIdSystem.js

@@ -42,25 +42,25 @@ export const identityLinkSubmodule = {
     // use protocol relative urls for http or https
     const url = `https://api.rlcdn.com/api/identity/envelope?pid=${configParams.pid}${hasGdpr ? '&ct=1&cv=' + gdprConsentString : ''}`;
     let resp;
-    // if ats library is initialised, use it to retrieve envelope. If not use standard third party endpoint
-    if (window.ats) {
-      resp = function(callback) {
+    resp = function(callback) {
+      // Check ats during callback so it has a chance to initialise.
+      // If ats library is available, use it to retrieve envelope. If not use standard third party endpoint
+      if (window.ats) {
         window.ats.retrieveEnvelope(function (envelope) {
           if (envelope) {
             callback(JSON.parse(envelope).envelope);
           } else {
             getEnvelope(url, callback);
           }
         });
-      }
-    } else {
-      resp = function (callback) {
+      } else {
         getEnvelope(url, callback);
       }
-    }
+    };
+
     return {callback: resp};
   }
-}
+};
 // return envelope from third party endpoint
 function getEnvelope(url, callback) {
   ajax(url, response => {