message: fixed issue updating item amount
diff: @@ -33,11 +33,27 @@ function mapStateToProps(state: RootState, { item }: ProvidedProps): StoreProps
  type Props = ProvidedProps & StoreProps;
  interface State {
  + index: string;
  amount: number;
  }
  class ItemActions extends React.Component<Props, State> {
  - state: State = { amount: this.props.item.amount };
  + static getDerivedStateFromProps(nextProps: Props, prevState: State): State | null {
  + if (nextProps.item.index !== prevState.index) {
  + return {
  + index: nextProps.item.index,
  + amount: nextProps.item.amount
  + };
  + }
  +
  + return null;
  + }
  +
  + state: State = {
  + index: this.props.item.index,
  + amount: this.props.item.amount
  + };
  +
  private maximumSelector = createSelector(
  (props: Props) => props.item,
  (props: Props) => props.store,
  