cookbook: add jsonerror section

[domenkozar]

I have yet to figure out how to build the cabal project for the cookbook.

[alpmestan]

cabal new-build cookbook-jsonerror should do, I think.

[domenkozar]

Pushed a few fixed to make sure it compiles.

I'd also like to update .travis.yml to actually test this on CI, but I don't see how its possible to generate the file since https://github.com/haskell-servant/servant/pull/917 landed.

[alpmestan]

Hmm, I think you just need to mimic e.g doc/cookbook/db-sqlite-simple, i.e have your jsonerror example be handled the same way we handle any other cookbook example. That precise bit of the travis script IIRC isn't generated automatically.

[domenkozar]

Maybe those backjumps are still needed:

Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: cookbook-pagination-2.1 (user goal)
[__1] next goal: servant-pagination (dependency of cookbook-pagination)
[__1] rejecting: servant-pagination-2.1.0 (conflict: requires
TypeApplications)
[__1] rejecting: servant-pagination-2.0.0, servant-pagination-1.0.0 (conflict:
cookbook-pagination => servant-pagination>=2.1.0 && <3.0.0)
[__1] fail (backjumping, conflict set: cookbook-pagination,
servant-pagination)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: cookbook-pagination,
servant-pagination

[tchoutri]

Hi @domenkozar! Could you please rebase this PR? We intend to have before the next major release of Servant. :)

[domenkozar]

I think this should be just part of servant, I'll add a TODO.