Why does it improve ng-repeat performance?

Let's suppose a function called refreshList aiming to call a REST API to retrieve a JSON array containing items.

$scope.refreshList = function () {
  // assuming getting the response object from REST API (Json) here
  $scope.items = response.data.listItems;  
}

And a basic ng-repeat on the HTML side:

<div ng-repeat="item in items track by item.id">

Then, I added a onPullToRefresh function, triggered by this directive, aiming to trigger a refresh of the whole list.

$scope.onPullToRefresh = function () {
  $scope.items = []; 
  $scope.refreshList();
} 

It's HTML is:

<ion-refresher on-refresh="onPullToRefresh()">
</ion-refresher>

The issue is that some pull-to-refresh (while scrolling to the top) can crash the app randomly...

Thus, I decided to alter the $scope.onPullToRefresh function like this:

$scope.onPullToRefresh = function () {
  //$scope.items = [];  commenting this line, causing the potential memory leak and the crash of the app
  $scope.refreshList();  
}

With this update, the app never crashes any more on my iOS device :)

However, I don't figure out what is the main difference by keeping the line emptying the array.
Does it impact directly the ng-repeat directive, causing some mess since the REST API's promise would reassign the content immediatly?
Indeed, Xcode IDE (since cordova app) indicated this error before applying this fix: EXC_BAD_ACCESS.

What might be the reason of this behavior?

I'm pointing out that Ionic (the framework I'm using) is fully tested with Angular 1.2.17 currently, so I'm using this version.