message: Allowed partial State with optional keys
diff: @@ -3,17 +3,17 @@ import withStateNavigator from './withStateNavigator';
  import { StateNavigator } from 'navigation';
  import { NavigationLinkProps } from './Props';
  import * as React from 'react';
  -type NavigationLinkState = { link: string, active: boolean, crumb: number };
  +type NavigationLinkState = { link?: string, active?: boolean, crumb?: number };
  class NavigationLink extends React.Component<NavigationLinkProps, NavigationLinkState> {
  constructor(props, context) {
  super(props, context);
  var { stateNavigator } = props;
  var { crumbs } = stateNavigator.stateContext;
  - this.state = { link: undefined, active: false, crumb: crumbs.length };
  + this.state = { crumb: crumbs.length };
  }
  - static getDerivedStateFromProps({ acrossCrumbs, stateKey, navigationData, includeCurrentData, currentDataKeys, stateNavigator }, { crumb }) {
  + static getDerivedStateFromProps({ acrossCrumbs, stateKey, navigationData, includeCurrentData, currentDataKeys, stateNavigator }, { crumb }): NavigationLinkState {
  var { crumbs, state } = stateNavigator.stateContext;
  if (!acrossCrumbs && crumb !== crumbs.length)
  return null;
  