I am recently creating an application in which I wrote a function to receive photos from the user, but when I click on the select photo button, I get these errors and no window opens to select photos
I even searched for these errors on the internet and came to the conclusion that I need to put a question mark (?) after DropzoneViewController, but I get the error DartError: Unexpected null value.
Please help.

error text:

DartError: LateInitializationError: Field 'dropzoneViewController' has not been initialized.
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 296:3             throw_
packages/shopping_admin/features/media/controllers/media_controller.dart 26:31          get dropzoneViewController
packages/shopping_admin/features/media/controllers/media_controller.dart 117:48         selectLocalImages
dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                      runBody
dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 127:5                      _async
packages/shopping_admin/features/media/controllers/media_controller.dart 116:33         selectLocalImages
packages/shopping_admin/features/media/screens/media/widgets/media_uploader.dart 88:62  <fn>
packages/flutter/src/material/ink_well.dart 1170:21                                     handleTap
packages/flutter/src/gestures/recognizer.dart 351:24                                    invokeCallback
packages/flutter/src/gestures/tap.dart 656:11                                           handleTapUp
packages/flutter/src/gestures/tap.dart 313:5                                            [_checkUp]
packages/flutter/src/gestures/tap.dart 246:7                                            handlePrimaryPointer
packages/flutter/src/gestures/recognizer.dart 703:9                                     handleEvent
packages/flutter/src/gestures/pointer_router.dart 98:7                                  [_dispatch]
packages/flutter/src/gestures/pointer_router.dart 143:9                                 <fn>
dart-sdk/lib/_internal/js_dev_runtime/private/linked_hash_map.dart 21:7                 forEach
packages/flutter/src/gestures/pointer_router.dart 141:17                                [_dispatchEventToRoutes]
packages/flutter/src/gestures/pointer_router.dart 127:7                                 route
packages/flutter/src/gestures/binding.dart 501:5                                        handleEvent
packages/flutter/src/gestures/binding.dart 481:14                                       dispatchEvent
packages/flutter/src/rendering/binding.dart 450:11                                      dispatchEvent
packages/flutter/src/gestures/binding.dart 426:7                                        [_handlePointerEventImmediately]
packages/flutter/src/gestures/binding.dart 389:5                                        handlePointerEvent
packages/flutter/src/gestures/binding.dart 336:7                                        [_flushPointerEventQueue]
packages/flutter/src/gestures/binding.dart 305:9                                        [_handlePointerDataPacket]
lib/_engine/engine/platform_dispatcher.dart 1423:5                                      invoke1
lib/_engine/engine/platform_dispatcher.dart 336:5                                       invokeOnPointerDataPacket
lib/_engine/engine/pointer_binding.dart 405:30                                          [_sendToFramework]
lib/_engine/engine/pointer_binding.dart 225:7                                           onPointerData
lib/_engine/engine/pointer_binding.dart 1035:20                                         <fn>
lib/_engine/engine/pointer_binding.dart 948:7                                           <fn>
lib/_engine/engine/pointer_binding.dart 541:9                                           loggedHandler
dart-sdk/lib/_internal/js_dev_runtime/patch/js_allow_interop_patch.dart 188:27          _callDartFunctionFast1

media controller :

class MediaController extends GetxController {
  static MediaController get instance => Get.find();

  late DropzoneViewController dropzoneViewController;
  final RxBool showImagesUploaderSection = false.obs;
  final Rx<MediaCategory> selectedPath = MediaCategory.folders.obs;
  final RxList<ImageModel> selectedImagesToUpload = <ImageModel>[].obs;

  final MediaRepository mediaRepository = MediaRepository();

  

  Future<void> selectLocalImages() async {
    final files = await dropzoneViewController.pickFiles(
      multiple: true,
      mime: ['image/jpg', 'image/png'],
    );

    if (files.isNotEmpty) {
      for (var file in files) {
        if (file is html.File) {
          final bytes = await dropzoneViewController.getFileData(file);
          final image = ImageModel(
            url: '',
            file: file,
            folder: '',
            filename: file.name,
            localImageToDisplay: Uint8List.fromList(bytes),
          );
          selectedImagesToUpload.add(image);
        }
      }
    }
  }