Check for a null UsbManager object

Apparently this can happen on some (broken?) devices

app/src/main/java/com/limelight/binding/input/ControllerHandler.java

@@ -365,6 +365,7 @@ public class ControllerHandler implements InputManager.InputDeviceListener, UsbD
         // Count all USB devices that match our drivers
         if (PreferenceConfiguration.readPreferences(context).usbDriver) {
             UsbManager usbManager = (UsbManager) context.getSystemService(Context.USB_SERVICE);
+            if (usbManager != null) {
                 for (UsbDevice dev : usbManager.getDeviceList().values()) {
                     // We explicitly check not to claim devices that appear as InputDevices
                     // otherwise we will double count them.
@@ -375,6 +376,7 @@ public class ControllerHandler implements InputManager.InputDeviceListener, UsbD
                     }
                 }
             }
+        }
 
         if (PreferenceConfiguration.readPreferences(context).onscreenController) {
             LimeLog.info("Counting OSC gamepad");

app/src/main/java/com/limelight/binding/input/driver/UsbDriverService.java

@@ -287,7 +287,7 @@ public class UsbDriverService extends Service implements UsbDriverListener {
     }
 
     private void start() {
-        if (started) {
+        if (started || usbManager == null) {
             return;
         }