fix(grid): add nullish for set items

Author: AlexAndriesUiPath

Diff for: projects/angular/components/ui-grid/src/filters/ui-grid-dropdown-filter.directive.ts

@@ -53,8 +53,8 @@ export class UiGridDropdownFilterDirective<T> extends UiGridFilterDirective<T> i
      */
     @Input()
     set items(value: IDropdownOption[]) {
-        this._items = value;
-        this.suggestItems = value.map((item, idx) => ({
+        this._items = value ?? [];
+        this.suggestItems = this._items.map((item, idx) => ({
             id: idx + 1,
             text: item.label,
             data: item.value,