Fix NPE in AudioSwitchPreferenceController

Change-Id: Ic97d1a6269a6d98ffd15a9b512f6ae24ff1c5b5e
Test: Unit Test to verify nullness
Bug: 338892614

src/com/android/settings/sound/AudioSwitchPreferenceController.java

@@ -242,6 +242,10 @@ public abstract class AudioSwitchPreferenceController extends BasePreferenceCont
             return connectedDevices;
         }
         final List<BluetoothDevice> devices = leAudioProfile.getConnectedDevices();
+        if (devices == null) {
+          Log.d(TAG, "No connected LeAudioProfile devices");
+          return connectedDevices;
+        }
         for (BluetoothDevice device : devices) {
             if (device.isConnected() && isDeviceInCachedList(device)) {
                 connectedDevices.add(device);