Support GraphQLErrorBuilder as controller method argument

[bclozel]

Our @GraphQlExceptionHandler example in the reference documentation shows the following:

@GraphQlExceptionHandler
public GraphQLError handle(BindException ex) {
	return GraphQLError.newError().errorType(ErrorType.BAD_REQUEST).message("...").build();
}

Doing so would return the error in the error map, but would miss critical information like "path" and "location".
You can get a better result with:

@GraphQlExceptionHandler
public GraphQLError handle(DataFetchingEnvironment environment, IllegalStateException ex) {
	return GraphqlErrorBuilder.newError(environment).errorType(ErrorType.BAD_REQUEST).message("...").build();
}

We should consider whether we should document this approach, or make available a GraphqlErrorBuilder parameter for error handlers with location/path information available from the environment.

[rstoyanchev]

That looks like an oversight. In our own default handling we use GraphQlErrorBuilder, and wherever there is a DataFetchingEnvironment we should be using it.

make available a GraphqlErrorBuilder parameter for error handlers

That makes sense to do, perhaps in DataFetchingEnvironmentMethodArgumentResolver.