Selected Nurse made not required

lib/views/pages/device_transfer/request_device_transfer.dart

@@ -62,7 +62,7 @@ class _RequestDeviceTransferState extends State<RequestDeviceTransfer> {
     _transferModel.destFloorId = _assetDestination.floor?.id;
     _transferModel.destDepartmentId = _assetDestination.department?.id;
     _transferModel.destRoomId = _assetDestination.room?.id;
-    _transferModel.receiverEndUserId = _selectedNurse.id;
+    _transferModel.receiverEndUserId = _selectedNurse != null ? _selectedNurse.id : null;
     if (!_formKey.currentState.validate() || !(await _transferModel.validate(context))) {
       return;
     }
@@ -121,8 +121,8 @@ class _RequestDeviceTransferState extends State<RequestDeviceTransfer> {
                         _assetDestination.floor = null;
                         _assetDestination.department = null;
                         _selectedNurse = null;
-                        Provider.of<NurseProvider>(context,listen: false).siteId = value.id;
-                        Provider.of<NurseProvider>(context,listen: false).getData();
+                        Provider.of<NurseProvider>(context, listen: false).siteId = value.id;
+                        Provider.of<NurseProvider>(context, listen: false).getData();
                         setState(() {});
                       },
                     ),