Switch discardParsedErrorData from returning a () to an unconstrained a

[Jayshua]

As discussed in #224

[Jayshua]

Turned out it didn't even need the never call at all. 🤷‍♂

[dillonkearns]

Wow, that's nice and simple then. Thanks for this nice refinement 👍

I don't have access to a computer for a couple of weeks. I just gave you push access, though, so you can merge it and do an Elm package release (since Elm let's you publish if you can create a git tag). If you do a release, would you mind updating the Elm package release notes markdown file, too?

[Jayshua]

I'm happy to try stumbling through it :) Never published an Elm package before, so I'll have to look up how its done. Shall report back when I get a chance to work through it.

[dillonkearns]

I published this in the latest release! https://github.com/dillonkearns/elm-graphql/blob/master/CHANGELOG-ELM-PACKAGE.md#500---2019-12-16

Thanks again!