Flutter: Error: MissingPluginException(No implementation found for method getTemporaryDirectory on channel plugins.flutter.io/path_provider)

I'm using Flutter-web and I want to export a pdf. I'm using the pdf package and i'm trying to implement a simple example from their documentation. To be more specific, I have a file called export_pdf.dart and the code inside it is the following.

import 'package:pdf/pdf.dart';
import 'package:pdf/widgets.dart';
import 'package:universal_io/io.dart';
import 'package:path_provider/path_provider.dart';

exportPdf() async {
  final pdf = Document();

  pdf.addPage(Page(
      pageFormat: PdfPageFormat.a4,
      build: (Context context) {
        return Center(
          child: Text("Hello World"),
        ); // Center
      })); // Page

  final output = await getTemporaryDirectory();
  final file = File("${output.path}/example.pdf");
  await file.writeAsBytes(await pdf.save());
}

When i'm calling the exportPdf() function by clicking a button, i'm getting the following error.

Uncaught (in promise) Error: MissingPluginException(No implementation found for method getTemporaryDirectory on channel plugins.flutter.io/path_provider)

I've been searching for this issue for a long time, but no solution has fixed this one.

Even though the path_provider package is imported, the getTemporaryDirectory() is never called, like it doesn't exist.

I need also to mention that i'm using universal_io, instead of dart:io, because i'm using flutter_web.

This error shows up for every function i'm calling and exists inside the path_provider/path_provider.dart file. I've also added inside path_provider/path_provider.dart a simple print function and i'm getting an error that the method is not found.

Thank you for your time.