BTW, the tracking code sends a request to your server for each ajax request? That looks like a big cost to end user (duplicated number of HTTP requests a browser makes).
Error: obj is undefined this.getTrackingCode@https://demo-dot-latenlog.appspot.com/static/js/out/common.j... this.save/<@https://demo-dot-latenlog.appspot.com/static/js/out/common.j... $http/promise.success/<@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... processQueue@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... scheduleProcessQueue/<@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... $RootScopeProvider/this.$get</Scope.prototype.$eval@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... $RootScopeProvider/this.$get</Scope.prototype.$digest@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... $RootScopeProvider/this.$get</Scope.prototype.$apply@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... done@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... completeRequest@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... requestLoaded@https://ajax.googleapis.com/ajax/libs/angularjs/1.4.9/angula... angular.js:12722:18