Add guards for restoreInstanceState (issue 11982812)

Change-Id: Ic4c632a956130ab28843085490dc1badb39b0e8c
diff --git a/src/com/android/launcher3/LauncherModel.java b/src/com/android/launcher3/LauncherModel.java
index 4d9dff9..74f28b3 100644
--- a/src/com/android/launcher3/LauncherModel.java
+++ b/src/com/android/launcher3/LauncherModel.java
@@ -2298,7 +2298,7 @@
                 r = new Runnable() {
                     public void run() {
                         Callbacks callbacks = tryGetCallbacks(oldCallbacks);
-                        if (callbacks != null) {
+                        if (callbacks != null && currentScreen >= 0) {
                             callbacks.onPageBoundSynchronously(currentScreen);
                         }
                     }