Union type issue for flutter web on release build mode

[dioseltorre]

When running the release build for flutter web, this error has occurred. Our graphql api returns a union type (please see schema below). Note that it's working well on debug mode and this only happens on release build.

main.dart.js:4234 Uncaught TypeError: Instance of 'minified:H0': type 'minified:H0' is not a subtype of type 'minified:ka'
    at Object.c (main.dart.js:4234:3)
    at Object.aMC (main.dart.js:4856:18)
    at kz.b1i [as a] (main.dart.js:4851:3)
    at kz.b1x (main.dart.js:4823:10)
    at main.dart.js:78762:13
    at az2.a (main.dart.js:5427:62)
    at az2.$2 (main.dart.js:39326:14)
    at Object.I (main.dart.js:5413:10)
    at as0.WN (main.dart.js:78796:10)
    at as0.$1 (main.dart.js:78751:19)

The issue occurred after executing this request,

client.request(request).listen((res) async {
      if (res.hasErrors) {
        ....
        return;
      }

      final data = res.data?.memberLogin;
      if (data?.G__typename == 'Member') {
        final res = data as GMemberLoginData_memberLogin__asMember ;
        ....
      } else if (data?.G__typename == 'EmailRegistration') {
        final res = data as GMemberLoginData_memberLogin__asEmailRegistration;
        ...
      }
    });

When I logged the data from the response above, I only got this information.

GMemberLoginData {
  G__typename=GuestMutation,
  memberLogin=GMemberLoginData_memberLogin__base {
    G__typename=Member ,
  },
}

Mutation

mutation MemberLogin($foo: String!, $foo1: String!) {
  memberLogin(foo: $foo, foo1: $foo1) {
    ... on EmailRegistration {
      __typename
      somefield
    }
    ... on Member {
      __typename
      somefield
    }
  }
}

Schema

type Mutation {
  memberLogin(foo: String!, foo1: String!): LoginResult!
}

union LoginResult = Member | EmailRegistration

Anyone have an idea regarding this issue?

[sebastianandreasson]

I'm also seeing this issue on web in release mode, does anyone know a workaround?

[bgparkerdev]

Running into this also. Seeing the same thing as the OP, it prints out the __base type instead of the concrete type. In debug mode the concrete type is printed out as expected.

Only workaround I've found is to build web in profile mode.

[Rydeard]

Running into the same issue now while trying to port our production app to web.

Has anyone been able to patch this?

@smkhalsa I understand you've been busy with other projects, but could you share your thoughts on what might be causing this issue?

[bgparkerdev]

@Rydeard The fix is checked into gql-dart https://github.com/gql-dart/gql/commit/85f6df5c785844a96c1e49b772b16e2f61a793b1 . You will have to fork ferry and update it to grab the latest gql-dart, until the ferry dependencies are updated.