Fix NPE by initializing notification manager

- initializeSatelliteSystemNotification should be called before
  registerForSatelliteProvisionStateChanged

Bug: 378782898
Test: atest SatelliteControllerTest
FLAG: com.android.internal.telephony.flags.carrier_roaming_nb_iot_ntn
Change-Id: Ib9f083a3a6c956ff50a617a0775ffa735f9c92d3
diff --git a/src/com/android/phone/satellite/accesscontrol/SatelliteAccessController.java b/src/com/android/phone/satellite/accesscontrol/SatelliteAccessController.java
index 4957225..ef169de 100644
--- a/src/com/android/phone/satellite/accesscontrol/SatelliteAccessController.java
+++ b/src/com/android/phone/satellite/accesscontrol/SatelliteAccessController.java
@@ -527,13 +527,13 @@
                         + satelliteSubscriberProvisionStatus);
             }
         };
+        initializeSatelliteSystemNotification(context);
         result = mSatelliteController.registerForSatelliteProvisionStateChanged(
                 mInternalSatelliteProvisionStateCallback);
         plogd("registerForSatelliteProvisionStateChanged result: " + result);
 
         // Init the SatelliteOnDeviceAccessController so that the S2 level can be cached
         initSatelliteOnDeviceAccessController();
-        initializeSatelliteSystemNotification(context);
         registerLocationModeChangedBroadcastReceiver(context);
         registerDefaultSmsAppChangedBroadcastReceiver(context);
     }
@@ -1442,6 +1442,10 @@
         );
         notificationChannel.setSound(null, null);
         mNotificationManager = context.getSystemService(NotificationManager.class);
+        if(mNotificationManager == null) {
+            ploge("initializeSatelliteSystemNotification: notificationManager is null");
+            return;
+        }
         mNotificationManager.createNotificationChannel(notificationChannel);
 
         createAvailableNotifications(context);