GTM issue fixed - not yet tested

"HelpHero.identify expects a valid number or string as the first argument, recieved: undefined Falling back to anonymous user tracking for this session"

frontend/angular/src/app/services/google-tag-manager.service.ts

@@ -27,16 +27,13 @@ export class GoogleTagManagerService {
         return window['dataLayer'];
     }
 
-    private clearDataLayer() {
-        const window = this.browserGlobals.windowRef();
-        window['dataLayer'] = [{
-            'gtm.start': new Date().getTime(),
-            event: 'gtm.js'
-        }];
-    }
-
     private pushOnDataLayer(obj: object) {
         const dataLayer = this.getDataLayer();
+
+        if(obj) {
+            obj['gtm.start'] = new Date().getTime(),
+            obj['event'] = 'gtm.js'
+        }
         dataLayer.push(obj);
     }
 
@@ -65,11 +62,10 @@ export class GoogleTagManagerService {
     }
 
     public pushTag(item: object) {        
-        this.clearDataLayer();
+        this.pushOnDataLayer(item);
         
         if (!this.isLoaded) {
             this.addGtmToDom();
         }
-        this.pushOnDataLayer(item);
     }
 }
\ No newline at end of file