message: Removed defensive default
  Unmounted style only called when there's at least one crumb
diff: @@ -5,7 +5,7 @@ import PhotoZoom from './PhotoZoom';
  export default () => (
  <NavigationMotion
  unmountedStyle={(state, data, crumbs) => {
  - var {state: previousState, data: previousData} = crumbs[crumbs.length - 1] || {};
  + var {state: previousState, data: previousData} = crumbs[crumbs.length - 1];
  var sharePhoto = state.key === 'photo' && !(previousState.key === 'tweet' && previousData.id === data.id);
  return !sharePhoto ? {translate: 100, scale: 1, opacity: 1} : {translate: 0, scale: 1, opacity: 0};
  }}
  