Fixing voicemail notification bug

Added a check for null notification tags when updating voicemail notifications.

Bug: 67607115
Test: manual and unit test
PiperOrigin-RevId: 172121860
Change-Id: If9fd6ca972a5a1dbd48a9c529f3cb46c3c93fa2a
diff --git a/java/com/android/dialer/app/calllog/VisualVoicemailUpdateTask.java b/java/com/android/dialer/app/calllog/VisualVoicemailUpdateTask.java
index 2544483..e30623b 100644
--- a/java/com/android/dialer/app/calllog/VisualVoicemailUpdateTask.java
+++ b/java/com/android/dialer/app/calllog/VisualVoicemailUpdateTask.java
@@ -121,7 +121,8 @@
       if (notification.getId() != VisualVoicemailNotifier.NOTIFICATION_ID) {
         continue;
       }
-      if (!notification.getTag().startsWith(VisualVoicemailNotifier.NOTIFICATION_TAG_PREFIX)) {
+      if (TextUtils.isEmpty(notification.getTag())
+          || !notification.getTag().startsWith(VisualVoicemailNotifier.NOTIFICATION_TAG_PREFIX)) {
         continue;
       }
       String uri =