Fix for NPE in KeyguardUpdateMonitor

Fix: 359233176
Test: Not tested
Flag: NONE not flagged, simply returns an invalid value instead of
crashing

Change-Id: I05ab023967c8a5b1bb8b6f9bb1045df3c69b7437
diff --git a/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java b/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
index 9b45fa4..f731186 100644
--- a/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
+++ b/packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java
@@ -3811,7 +3811,8 @@
         if (!mSimDatas.containsKey(subId)) {
             refreshSimState(subId, SubscriptionManager.getSlotIndex(subId));
         }
-        return mSimDatas.get(subId).slotId;
+        SimData simData = mSimDatas.get(subId);
+        return simData != null ? simData.slotId : SubscriptionManager.INVALID_SUBSCRIPTION_ID;
     }
 
     private final TaskStackChangeListener mTaskStackListener = new TaskStackChangeListener() {