How to receive error while inserting in store?

I am using angular-indexedDB for indexedDB in AngularJS. I want to receive error if insert is not successful. But I am not getting any error it just comes out of the function if I run the same code twice as I have made name unique.

Error:

ConstraintError return _this.store.add(item);

ConstraintError req = this.store.openCursor();

Code:

angular.module('myModuleName')
  .controller('myControllerName', function($scope, $indexedDB) {

    $scope.objects = [];

    $indexedDB.openStore('people', function(store){

      store.insert({"ssn": "444-444-222-111","name": "John Doe", "age": 57}).then(function(e){console.log('inside insert');});

      store.getAll().then(function(people) {  
        // Update scope
        $scope.objects = people;
      });
    });
});