message: Fix dropdown negative wraparound for keyboard accessibility
diff: @@ -269,7 +269,7 @@ export default class Dropdown extends React.Component<IProps, IState> {
  private prevOption(optionKey: string): string {
  const keys = Object.keys(this.childrenByKey);
  const index = keys.indexOf(optionKey);
  - return keys[(index - 1) % keys.length];
  + return keys[index <= 0 ? keys.length - 1 : (index - 1) % keys.length];
  }
  private scrollIntoView(node: Element) {
  