onInputChange method private presentation

  private onInputChange(): void {
    if (!this._open) this.open();
    const query = this.input!.value.toLowerCase();
    const filtered = this.flat.filter(
      (o) =>
        o.label.toLowerCase().includes(query) ||
        o.value.toLowerCase().includes(query),
    );
    this._highlighted = -1;
    this.renderOptions(filtered);
  }