Fix NPE if workspace is not created yet

Change-Id: I0c8976a8497e2059ec7b2cda3d56eb965a532765
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index ba34c13..2b08bf0 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -492,7 +492,7 @@
      * ensure the custom content page is added or removed if necessary.
      */
     protected void invalidateHasCustomContentToLeft() {
-        if (mWorkspace.getScreenOrder().isEmpty()) {
+        if (mWorkspace == null || mWorkspace.getScreenOrder().isEmpty()) {
             // Not bound yet, wait for bindScreens to be called.
             return;
         }