graphql-ws expects ErrorMessage on error, and Absinthe.GraphqlWS.Message.Error supports providing it, but Absinthe.GraphqlWS.Transport.handle_inbound uses handle_init callback return only as error id.

I think this library has two paths to resolve this:

1. Add possibility to add payload provided by developer (expect handle_init return something like {:error, {id, payload}, socket})
2. Generate error inside this library