Flutter platform specific packages for web won't build for linux using kIsWeb

I have 2 web specific flutter packages, dart:html and dart:js for web and path_provider for other platforms. My problem is that this project will compile for web but crashes when I try to build for linux with the following errors. How can I build a multiplatform app to download files? flutter clean and flutter pub get changed nothing.

ERROR: lib/ui/views/file_download_view.dart:15:8: Error: Not found: 'dart:html'
ERROR: import 'dart:html' as html;
ERROR:        ^
ERROR: lib/ui/views/file_download_view.dart:16:8: Error: Not found: 'dart:js'
ERROR: import 'dart:js' as js;
ERROR:        ^
ERROR: lib/ui/views/file_download_view.dart:118:12: Error: Method not found: 'Blob'.
ERROR:       html.Blob(<Object>[bytes]),
ERROR:            ^^^^
ERROR: lib/ui/views/file_download_view.dart:117:8: Error: Undefined name 'context'.
ERROR:     js.context.callMethod("saveAs", <Object>[
ERROR:        ^^^^^^^
ERROR: Unhandled exception:
Building Linux application...                                           
Build process failed

I thought kIsWeb is supposed to separate them but the compiler crashes anyway. My code to separate them looks like this.

ElevatedButton.icon(
  onPressed: () {
    kIsWeb ? downloadWebFile(user) : downloadMobileFile(user);
}, 

My web specific code is

import 'dart:html' as html;
import 'dart:js' as js;
....
js: ^0.6.4
html: ^0.15.0

These show a linter warning "avoid using web-only libraries outside Flutter web plugin packages. How can I avoid that?

 Future<void> downloadWebFile(User user) async {
    final navigator = Navigator.of(context);

    final storage = FlutterSecureStorage();

    String? token = await storage.read(key: 'jwt');

    Response<List<int>> rs;

    rs = await Dio().get<List<int>>(
      user.fileUrl,
      options: Options(
          headers: {HttpHeaders.authorizationHeader: 'Bearer $token'},
          responseType: ResponseType.bytes),
      onReceiveProgress: (rcv, total) {
        received =
            'received: ${rcv.toStringAsFixed(0)} out of total: ${total.toStringAsFixed(0)}';

        setState(
          () {
            progress = ((rcv / total) * 100).toStringAsFixed(0);
          },
        );

        if (progress == '100') {
          setState(
            () {
              isDownloaded = true;
            },
          );
        } else if (double.parse(progress) < 100) {}
      },
    );

    if (progress == '100') {
      downloading = false;

      isDownloaded = true;

      save(json.encode(rs.data), user.downloadFileName);

      user.snackBarType = SnackBarType.success;

      user.snackBarMessage = 'File downloaded successfully ';

      navigator.pushNamedAndRemoveUntil(RoutePaths.matter, (route) => false);
    } else {
      downloading = false;

      user.snackBarType = SnackBarType.failure;

      user.snackBarMessage = 'File download failed';

      navigator.pushNamedAndRemoveUntil(RoutePaths.matter, (route) => false);
    }
  }

Non web specific code:

  Future<void> downloadMobileFile(User user) async {
    setState(
      () {
        downloading = true;
        filename = user.downloadFileName;
      },
    );

    final navigator = Navigator.of(context);

    bool hasPermission = await _requestWritePermission();
    if (!hasPermission) return;

    String savePath = await getFilePath(user.downloadFileName);

    final storage = FlutterSecureStorage();

    String? token = await storage.read(key: 'jwt');

    Dio dio = Dio();
    dio.download(
      user.fileUrl,
      savePath,
      options: Options(
        headers: {HttpHeaders.authorizationHeader: 'Bearer $token'},
      ),
      onReceiveProgress: (rcv, total) {
        received =
            'received: ${rcv.toStringAsFixed(0)} out of total: ${total.toStringAsFixed(0)}';

        setState(
          () {
            progress = ((rcv / total) * 100).toStringAsFixed(0);
          },
        );

        if (progress == '100') {
          setState(
            () {
              isDownloaded = true;
            },
          );
        } else if (double.parse(progress) < 100) {}
      },
      deleteOnError: true,
    ).then(
      (_) {
        setState(
          () {
            if (progress == '100') {
              downloading = false;

              isDownloaded = true;

              user.snackBarType = SnackBarType.success;

              user.snackBarMessage = 'File downloaded successfully';

              navigator.pushNamedAndRemoveUntil(
                  RoutePaths.matter, (route) => false);
            } else {
              downloading = false;

              user.snackBarType = SnackBarType.failure;

              user.snackBarMessage = 'File download failed';
            }
          },
        );
      },
    );



Future<bool> _requestWritePermission() async {
    await Permission.storage.request();
    return await Permission.storage.request().isGranted;
  }

  Future<String> getFilePath(uniqueFileName) async {
    String path = '';

    Directory dir = await getApplicationDocumentsDirectory();

    path = '${dir.path}/$uniqueFileName';

    print("file download path");

    print(path);

    return path;
  }
}