From 6452e92ac9436b712a47c51aade2b656f5f4917e Mon Sep 17 00:00:00 2001
From: David Rowe <david@ctrlaltstudio.com>
Date: Thu, 25 May 2017 11:28:26 +1200
Subject: [PATCH] Hand controller data may not be valid

---
 scripts/system/libraries/WebTablet.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scripts/system/libraries/WebTablet.js b/scripts/system/libraries/WebTablet.js
index a3090f05e7..5168e2340d 100644
--- a/scripts/system/libraries/WebTablet.js
+++ b/scripts/system/libraries/WebTablet.js
@@ -51,14 +51,18 @@ function calcSpawnInfo(hand, tabletHeight) {
         hand = NO_HANDS;
     }
 
+    var handController = null;
     if (HMD.active && hand !== NO_HANDS) {
+        handController = getControllerWorldLocation(hand, true);
+    }
+
+    if (handController && handController.valid) {
         // Orient tablet per hand orientation.
         // Angle it back similar to holding it like a book.
         // Make it horizontal.
         // Move tablet up so that hand is at bottom.
         // Move tablet back so that hand is in front.
 
-        var handController = getControllerWorldLocation(hand, true);
         var position = handController.position;
         var rotation = handController.rotation;