code: function makeHooksSafe(routes, store) {
    if (Array.isArray(routes)) {
      return routes.map(route => makeHooksSafe(route, store));
    }
  
    const onEnter = routes.onEnter;
  
    if (onEnter) {
      routes.onEnter = function safeOnEnter(...args) {
        try {
          store.getState();
        } catch (err) {
          if (onEnter.length === 3) {
            args[2]();
          }
  
          // There's no store yet so ignore the hook
          return;
        }
  
        onEnter.apply(null, args);
      };
    }
  
    if (routes.childRoutes) {
      makeHooksSafe(routes.childRoutes, store);
    }
  
    if (routes.indexRoute) {
      makeHooksSafe(routes.indexRoute, store);
    }
  
    return routes;
  }
docs: Wrap the hooks so they don't fire if they're called before the store is initialised. This only happens when doing the first client render of a route that has an onEnter hook