notFoundText shouldn't be displayed when loading async data

[shyamal890]

When [loading] flag is set notFoundText shouldn't be triggered as the [items] array is still waiting to be populated by an async operation.

Example Plunker: https://plnkr.co/edit/XU3qdu?p=preview

Checkout the first example.

[anjmao]

@shyamal890 Thanks for reporting, good catch!

[anjmao]

This line here is missing some logic https://github.com/ng-select/ng-select/blob/master/src/ng-select/ng-select.component.ts#L369, need to add check if !isLoading

const empty = this.itemsList.filteredItems.length === 0;
return (empty && !this._isTypeahead && !this.isLoading) ||
       (empty && this._isTypeahead && this.filterValue && !this.isLoading);