From c4806752d7c38c08316d4df6e5f25dce2ea87164 Mon Sep 17 00:00:00 2001
From: Greg Hardin <greg@icebrg.io>
Date: Fri, 19 Oct 2018 11:35:40 -0700
Subject: [PATCH] Fixing bug caused by #8917

---
 packages/gatsby/src/bootstrap/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/gatsby/src/bootstrap/index.js b/packages/gatsby/src/bootstrap/index.js
index 8adc768cdd327..261007bd6d7a5 100644
--- a/packages/gatsby/src/bootstrap/index.js
+++ b/packages/gatsby/src/bootstrap/index.js
@@ -73,7 +73,7 @@ module.exports = async (args: BootstrapArgs) => {
   )
 
   // theme gatsby configs can be functions or objects
-  if (config.__experimentalThemes) {
+  if (config && config.__experimentalThemes) {
     const themesConfig = await Promise.mapSeries(
       config.__experimentalThemes,
       async ([themeName, themeConfig]) => {