Add error handle for device that not support Bluetooth

- Add LocalBluetoothManager null check for device that
  not support Bluetooth
- Add test to verify when LocalBluetoothManager is null
  will not crash

Bug: 110712414
Test: make -j42 RunSettingsRoboTests
Change-Id: Ib506a0206cfcfdfec60bdfcf9a1944338a7ab729

tests/robotests/src/com/android/settings/bluetooth/BluetoothDeviceUpdaterTest.java

@@ -167,4 +167,20 @@ public class BluetoothDeviceUpdaterTest {
 
         assertThat(mBluetoothDeviceUpdater.isDeviceConnected(mCachedBluetoothDevice)).isFalse();
     }
+
+    @Test
+    public void registerCallback_localBluetoothManagerNull_shouldNotCrash() {
+        mBluetoothDeviceUpdater.mLocalManager = null;
+
+        // Shouldn't crash
+        mBluetoothDeviceUpdater.registerCallback();
+    }
+
+    @Test
+    public void unregisterCallback_localBluetoothManagerNull_shouldNotCrash() {
+        mBluetoothDeviceUpdater.mLocalManager = null;
+
+        // Shouldn't crash
+        mBluetoothDeviceUpdater.unregisterCallback();
+    }
 }