fix(hierarchicalMenu): handle cases where no results after a search

fixed in the helper: https://github.com/algolia/algoliasearch-helper-
js/commit/d0337d3fb2916550f157696909532a973f1cced2

fixes #385

Author: vvo

npm-shrinkwrap.json

@@ -67,7 +67,7 @@
   },
   "dependencies": {
     "algoliasearch": "^3.9.0",
-    "algoliasearch-helper": "^2.6.4",
+    "algoliasearch-helper": "^2.6.5",
     "classnames": "^2.2.0",
     "events": "^1.1.0",
     "hogan.js": "^3.0.2",