From af88f4c7126150cf81333d3da0b49738932ff4ed Mon Sep 17 00:00:00 2001
From: finscn <fins@163.com>
Date: Fri, 27 Oct 2017 22:49:20 +0800
Subject: [PATCH] Add `null checking` for `document.activeElement`

Detail is at  https://github.com/dataarts/dat.gui/issues/159
---
 src/dat/gui/GUI.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/dat/gui/GUI.js b/src/dat/gui/GUI.js
index 803ee1b..a327452 100644
--- a/src/dat/gui/GUI.js
+++ b/src/dat/gui/GUI.js
@@ -468,7 +468,7 @@ GUI.TEXT_CLOSED = 'Close Controls';
 GUI.TEXT_OPEN = 'Open Controls';
 
 GUI._keydownHandler = function(e) {
-  if (document.activeElement.type !== 'text' &&
+  if (document.activeElement && document.activeElement.type !== 'text' &&
     (e.which === HIDE_KEY_CODE || e.keyCode === HIDE_KEY_CODE)) {
     GUI.toggleHide();
   }