change in initialization and condition access of dataLayer

Removed the global initialization of dataLayer and added conditional checks for dataLayer.

Ref - #506

assets/js/event-handler.js

@@ -1,8 +1,5 @@
 "use-strict";
 
-// Ensure dataLayer is defined Globally before using it
-window.dataLayer = window.dataLayer || [];
-
 const Toast = Swal.mixin({
   toast: true,
   position: 'center',
@@ -19,12 +16,14 @@ document.getElementById('bug-report').addEventListener('vl-bug-report', (e) => {
   if (e.detail.status === 200 || e.detail.status === 201) {
     const learningUnit = document.head.querySelector('meta[name="learning-unit"]').content;
     const task = document.head.querySelector('meta[name="task-name"]').content;
-    dataLayer.push({
-      event: "vl-bug-report",
-      "bug-type": e.detail.issues,
-      "learning-unit": learningUnit ? learningUnit : "",
-      "task-name": task ? task : ""
-    })
+    if (window.dataLayer) {
+      window.dataLayer.push({
+        event: "vl-bug-report",
+        "bug-type": e.detail.issues,
+        "learning-unit": learningUnit ? learningUnit : "",
+        "task-name": task ? task : ""
+      })
+    }
     Toast.fire({
       icon: 'success',
       iconColor: "white",
@@ -47,13 +46,15 @@ document.getElementById('bug-report').addEventListener('vl-bug-report', (e) => {
 function handleRatingSubmit(e) {
   const learningUnit = document.head.querySelector('meta[name="learning-unit"]').content;
   const task = document.head.querySelector('meta[name="task-name"]').content;
-  dataLayer.push({
-    event: "vl-rating-submit",
-    "rating": e.detail.rating,
-    "rating-value": e.detail.rating,
-    "learning-unit": learningUnit ? learningUnit : "",
-    "task-name": task ? task : ""
-  });
+  if (window.dataLayer) {
+    window.dataLayer.push({
+      event: "vl-rating-submit",
+      "rating": e.detail.rating,
+      "rating-value": e.detail.rating,
+      "learning-unit": learningUnit ? learningUnit : "",
+      "task-name": task ? task : ""
+    });
+  }
   Toast.fire({
     icon: 'success',
     iconColor: "white",