am 424781e2: Fix NPE in ConnectivityService.

* commit '424781e2e1a1f1447eea733ffd1dc0f8006b628e':
  Fix NPE in ConnectivityService.
diff --git a/services/java/com/android/server/ConnectivityService.java b/services/java/com/android/server/ConnectivityService.java
index fc87033..6e4aca7 100644
--- a/services/java/com/android/server/ConnectivityService.java
+++ b/services/java/com/android/server/ConnectivityService.java
@@ -1597,6 +1597,7 @@
                 if (checkType == prevNetType) continue;
                 if (mNetConfigs[checkType] == null) continue;
                 if (!mNetConfigs[checkType].isDefault()) continue;
+                if (mNetTrackers[checkType] == null) continue;
 
 // Enabling the isAvailable() optimization caused mobile to not get
 // selected if it was in the middle of error handling. Specifically