Breaking change introduced in 2.4.0 grpc-web flutter

[long1eu]

Using a commit after bb4eab0 generates this error. Seems like something changed in the way the request is made. I'm assuming is the headers.

I tried this against a local envoy proxy and with Google Cloud Run with ESPv2(envoy).

errors.dart:167 Uncaught Error: Bad state: Cannot add event after closing
    at Object.throw_ [as throw] (errors.dart:216)
    at _AsyncStreamController.new.addError (stream_controller.dart:633)
    at ClientCall.new.[_onRequestError] (call.dart:370)
    at xhr_transport.dart:71
    at Object._checkAndCall (operations.dart:324)
    at Object.dcall (operations.dart:329)
    at XMLHttpRequest.<anonymous> (html_dart2js.dart:37283)
    at xhr_transport.XhrTransportStream.new.terminate (xhr_transport.dart:148)
    at terminate.next (<anonymous>)
    at runBody (async_patch.dart:84)
    at Object._async [as async] (async_patch.dart:123)
    at xhr_transport.XhrTransportStream.new.terminate (xhr_transport.dart:146)
    at ClientCall.new.[_onRequestError] (call.dart:375)
    at xhr_transport.XhrTransportStream.new.[_onHeadersReceived] (xhr_transport.dart:116)
    at xhr_transport.dart:67
    at Object._checkAndCall (operations.dart:324)
    at Object.dcall (operations.dart:329)
    at XMLHttpRequest.<anonymous> (html_dart2js.dart:37283)

grpc web init:

// File created by
// Lung Razvan <long1eu>
// on 16/04/2020

import 'package:firebase/firebase.dart';
import 'package:grpc/grpc_web.dart' as js;
import 'package:grpc/src/client/channel.dart' show ClientChannel;

import 'init.dart' as base;

export 'package:grpc/grpc_web.dart' show CallOptions;
export 'package:grpc/src/client/channel.dart' show ClientChannel;

class InitConfig implements base.InitConfig {
  const InitConfig();

  @override
  ClientChannel get channel {
    if (Config.location == 'cloud') {
      return js.GrpcWebClientChannel.xhr(Uri.parse('https://${Config.endpoint}'));
    } else {
      return js.GrpcWebClientChannel.xhr(Uri.parse('http://localhost:8081'));
    }
  }

  @override
  js.CallOptions get options {
    return js.CallOptions(
      metadata: <String, String>{
        'x-api-key': '<key>',
      },
      providers: <js.MetadataProvider>[
        (Map<String, String> metadata, String url) async {
          if (app().auth().currentUser != null) {
            final String token = await app().auth().currentUser.getIdToken();
            metadata['authorization'] = 'Bearer $token';
          }
        },
      ],
    );
  }
}

Let me know if there is anything I can do to help identifying the bug and fixing it.
Thanks

[mraleph]

Does removing these three lines: https://github.com/grpc/grpc-dart/pull/369/files#diff-b5d4b67a950306222090fd9c916740320086a1241fc0052a8941002423e449cf fix it?

[long1eu]

I've removed this from lib/src/client/transport/xhr_transport.dart

    request.setRequestHeader('Content-Type', 'application/grpc-web+proto');
    request.setRequestHeader('X-User-Agent', 'grpc-web-dart/0.1');
    request.setRequestHeader('X-Grpc-Web', '1');

But the result is the same.

[long1eu]

UPDATE: It does work.

My fault. Seems like I've remove them from the pub version, not the one that I was actually using.

[mraleph]

We are going to revert offending change and publish a fixed version of the package, but most likely this is not going to happen earlier than next week.

I am also going to switch to envoy proxy for testing instead of grpcwebproxy, because it turns out that grpcwebproxy is too lax and did not catch this bug.

[mraleph]

We have published 2.8.0 which fixes the issue and we have switched our testing to use envoy proxy to catch this sort of errors earlier.