Fixes two TypeError exceptions when up/down arrow pressed (#2585)

* fixes `Cannot read property 'position' of undefined` error.

when using live search, if a user enters a value that does not return
any results and then presses the up/down arrows, this error occurs. this
commit fixes that error.

* fixes `Cannot read property 'index' of undefined` error.

when using live search, if a user enters a value that does not return
any results and then presses the up/down arrows, this error occurs. this
commit fixes that error.

Co-authored-by: RJ Regenold <[email protected]>

Author: rjregenold

js/bootstrap-select.js

@@ -2885,9 +2885,13 @@
             liActiveIndex = that.selectpicker.current.elements.length - 1;
           } else {
             activeLi = that.selectpicker.current.data[liActiveIndex];
-            offset = activeLi.position - activeLi.height;
 
-            updateScroll = offset < scrollTop;
+            // could be undefined if no results exist
+            if (activeLi) {
+              offset = activeLi.position - activeLi.height;
+
+              updateScroll = offset < scrollTop;
+            }
           }
         } else if (e.which === keyCodes.ARROW_DOWN || downOnTab) { // down
           // scroll to top and highlight first option
@@ -2897,15 +2901,19 @@
             liActiveIndex = that.selectpicker.view.firstHighlightIndex;
           } else {
             activeLi = that.selectpicker.current.data[liActiveIndex];
-            offset = activeLi.position - that.sizeInfo.menuInnerHeight;
 
-            updateScroll = offset > scrollTop;
+            // could be undefined if no results exist
+            if (activeLi) {
+              offset = activeLi.position - that.sizeInfo.menuInnerHeight;
+
+              updateScroll = offset > scrollTop;
+            }
           }
         }
 
         liActive = that.selectpicker.current.elements[liActiveIndex];
 
-        that.activeIndex = that.selectpicker.current.data[liActiveIndex].index;
+        that.activeIndex = (that.selectpicker.current.data[liActiveIndex] || {}).index;
 
         that.focusItem(liActive);