Fix NPE in ListsFragment.

Bug: 25694033
Bug: 25668829

Change-Id: I5254eed0c473fa8a9e801f4fa253d6fdfc885836
diff --git a/src/com/android/dialer/list/ListsFragment.java b/src/com/android/dialer/list/ListsFragment.java
index cf999e7..5294498 100644
--- a/src/com/android/dialer/list/ListsFragment.java
+++ b/src/com/android/dialer/list/ListsFragment.java
@@ -360,7 +360,7 @@
      * expands a voicemail in the call log.
      */
     public void updateTabUnreadCounts() {
-        if (mHasActiveVoicemailProvider) {
+        if (mHasActiveVoicemailProvider && mCallLogQueryHandler != null) {
             mCallLogQueryHandler.fetchVoicemailUnreadCount();
         }
     }