From 1a42593764076fdd26d64d4b4b3e98b56e6d40e0 Mon Sep 17 00:00:00 2001
From: kale-io <30478851+kale-io@users.noreply.github.com>
Date: Mon, 13 Nov 2017 23:56:49 +0200
Subject: [PATCH] Add extra check for undefined

---
 packages/gatsby-react-router-scroll/src/StateStorage.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/gatsby-react-router-scroll/src/StateStorage.js b/packages/gatsby-react-router-scroll/src/StateStorage.js
index dcaabaf7f8b31..0658b74b37134 100644
--- a/packages/gatsby-react-router-scroll/src/StateStorage.js
+++ b/packages/gatsby-react-router-scroll/src/StateStorage.js
@@ -48,6 +48,6 @@ export default class SessionStorage {
   getStateKey(location, key) {
     const locationKey = location.key
     const stateKeyBase = `${STATE_KEY_PREFIX}${locationKey}`
-    return key === null ? stateKeyBase : `${stateKeyBase}|${key}`
+    return (key === null || typeof key === `undefined`) ? stateKeyBase : `${stateKeyBase}|${key}`
   }
 }