[Companion] Dont crash if started with bluetooth off

Bug: 63068644
Test: Turn BT off, and ensure the attached bud doesn't reproduce
Change-Id: I0de5ba6d28d7195dd3ebc7a3af36f057c762de60
(cherry picked from commit 7a090a11ed00aa492684800de890f4df633409d8)
diff --git a/packages/CompanionDeviceManager/src/com/android/companiondevicemanager/DeviceDiscoveryService.java b/packages/CompanionDeviceManager/src/com/android/companiondevicemanager/DeviceDiscoveryService.java
index 3b29a6c..1e262314 100644
--- a/packages/CompanionDeviceManager/src/com/android/companiondevicemanager/DeviceDiscoveryService.java
+++ b/packages/CompanionDeviceManager/src/com/android/companiondevicemanager/DeviceDiscoveryService.java
@@ -77,7 +77,7 @@
 
     private BluetoothAdapter mBluetoothAdapter;
     private WifiManager mWifiManager;
-    private BluetoothLeScanner mBLEScanner;
+    @Nullable private BluetoothLeScanner mBLEScanner;
     private ScanSettings mDefaultScanSettings = new ScanSettings.Builder().build();
 
     private List<DeviceFilter<?>> mFilters;
@@ -185,7 +185,7 @@
             mBluetoothAdapter.startDiscovery();
         }
 
-        if (shouldScan(mBLEFilters)) {
+        if (shouldScan(mBLEFilters) && mBLEScanner != null) {
             mBLEScanCallback = new BLEScanCallback();
             mBLEScanner.startScan(mBLEScanFilters, mDefaultScanSettings, mBLEScanCallback);
         }
@@ -224,7 +224,7 @@
             unregisterReceiver(mBluetoothBroadcastReceiver);
             mBluetoothBroadcastReceiver = null;
         }
-        mBLEScanner.stopScan(mBLEScanCallback);
+        if (mBLEScanner != null) mBLEScanner.stopScan(mBLEScanCallback);
         if (mWifiBroadcastReceiver != null) {
             unregisterReceiver(mWifiBroadcastReceiver);
             mWifiBroadcastReceiver = null;
diff --git a/services/companion/java/com/android/server/companion/CompanionDeviceManagerService.java b/services/companion/java/com/android/server/companion/CompanionDeviceManagerService.java
index 4810f4f..f47b0d3 100644
--- a/services/companion/java/com/android/server/companion/CompanionDeviceManagerService.java
+++ b/services/companion/java/com/android/server/companion/CompanionDeviceManagerService.java
@@ -383,7 +383,7 @@
                                     findDeviceCallback,
                                     getServiceCallback());
                 } catch (RemoteException e) {
-                    throw new RuntimeException(e);
+                    Log.e(LOG_TAG, "Error while initiating device discovery", e);
                 }
             }