Dropdown with unselectable index 0 will not scroll to top on arrow_down with last index selected

[Slowey]

Demo:
https://plnkr.co/edit/k2xl65uBG8xsFVaX

Steps to reproduce:

1. Create a dropdown with an options group at element 1
2. Fill your dropdown with enough items to trigger a scrollbar (data-size=5 and 10 elements should do)
3. Open the dropdown and use arrow down to traverse the dropdown until you are at the last item.
4. Hit arrow down one last time. The selector will select the correct item, but your scroll bar will not be set to the top.

Environment:
Boostrap 4
Boostrap-select 1.13.17
jQuery version 3.4.1
Windows 10
Chrome 83.0.4103.97

Code that seems buggy:
bootstrap-select.js

line: 2876-2881:

else if (e.which === keyCodes.ARROW_DOWN || downOnTab) { // down
            index++; 
          if (index + position0 >= that.selectpicker.view.canHighlight.length) index = 0;

          if (!that.selectpicker.view.canHighlight[index + position0]) {
            index = index + 1 + that.selectpicker.view.canHighlight.slice(index + position0 + 1).indexOf(true);
          }
        }

This code selects the first highlightable index. In this case index = 1

Further down in the scroll to top code:
line: 2901-2911:

else if (e.which === keyCodes.ARROW_DOWN || downOnTab) { // down
          // scroll to top and highlight first option
          if (index === 0) {
            that.$menuInner[0].scrollTop = 0;

            liActiveIndex = 0;
          } else {
            activeLi = that.selectpicker.current.data[liActiveIndex];
            offset = activeLi.position - that.sizeInfo.menuInnerHeight;

            updateScroll = offset > scrollTop;
          }

Only scrolls to top if index === 0. Since index 0 is not highlightable. This has to check for the first highlightable index and not 0.

BR,
Lucas

[Slowey]

Tried the changes locally, seems to be working. Thanks!

[caseyjhol]

Released in v1.13.18!

[erdincozer]

I think I found a simple solution to this problem.
$('#country').selectpicker('destroy');
this code solves the problem.
Maybe you need to make similar changes as well.
$('#country').empty();
$('#country').html('<option value="-1" selected = "selected">- Please Country Select-</option>');
$("#country").val(-1);
$.ajax({ .........
In this way scroll to top