Check for a null intent in RemoteVvmTaskManager#onStartCommand.

https://developer.android.com/reference/android/app/Service#onstartcommand indicates that the intent parameter can be null if the service is being restarted after the process has gone away.

Bug: 138442946
Test: manual
Change-Id: I022a0fa830bd3e53204c86e8a87a132409ee9b1f
diff --git a/src/com/android/phone/vvm/RemoteVvmTaskManager.java b/src/com/android/phone/vvm/RemoteVvmTaskManager.java
index 50ac669..14030a1 100644
--- a/src/com/android/phone/vvm/RemoteVvmTaskManager.java
+++ b/src/com/android/phone/vvm/RemoteVvmTaskManager.java
@@ -226,6 +226,11 @@
         Assert.isMainThread();
         mTaskReferenceCount++;
 
+        if (intent == null) {
+            VvmLog.i(TAG, "received intent is null");
+            checkReference();
+            return START_NOT_STICKY;
+        }
         PhoneAccountHandle phoneAccountHandle = intent.getExtras()
                 .getParcelable(VisualVoicemailService.DATA_PHONE_ACCOUNT_HANDLE);
         int subId = PhoneAccountHandleConverter.toSubId(phoneAccountHandle);