Steps to reproduce:

1. Create host with at least two items: item#1, item#2
2. Open dashboard
3. Click add widget
4. Select pie chart, or any other widget for which data set: item list is available.
5. Add data set - item list, select two created items
6. Add widget, save dashboard
7. Delete the item that is displayed as the first one in the widget data
8. Open dashboard, reload the page is necessary, see the widget

Result:
Widget is loading infinitely, console error is displayed:

Could not update widget TypeError: dataset.itemids.entries is not a function

See screenshot:

Expected:
Widget should be working correctly with items that are left in data set, no errors should be displayed.