Make building a fresh project more reliable on NixOS

[YellowOnion]

$ stack install godot-haskell:exe:godot-haskell-project-generator
Error parsing targets: Unknown local package: godot-haskell
$ cd godot-haskell
$ stack install godot-haskell:exe:godot-haskell-project-generator --nix
copying path '/nix/store/ciilhm2shxjfjvhavrzhcvrhpbkcr1lq-source' from 'https://cache.nixos.org'...
error: attribute 'ghc8103' missing, at (string):1:29
(use '--show-trace' to show detailed location information)

nix-shell                                                                                                            ~/dev/godot-haskell
these derivations will be built:
  /nix/store/jqpap7jxx2y225qcpd9m4dqvqi0hdpla-godot-haskell-classgen-0.1.0.0.drv
  /nix/store/abl0592viapajllvy8kawy4fj5rp7cpa-ghc-8.6.4-with-packages.drv
building '/nix/store/jqpap7jxx2y225qcpd9m4dqvqi0hdpla-godot-haskell-classgen-0.1.0.0.drv'...
setupCompilerEnvironmentPhase
Build with /nix/store/m2qcxljyvg1225xc55nc2zsrgd9jx8r6-ghc-8.6.4.
unpacking sources
unpacking source archive /nix/store/35ilcf7gxzgvgm6mlx5w1mdpyxc4rj9b-classgen
source root is classgen
patching sources
godot-haskell-classgen.cabal is up-to-date
compileBuildDriverPhase
setupCompileFlags: -package-db=/build/setup-package.conf.d -j4 -threaded
[1 of 1] Compiling Main             ( /nix/store/4mdp8nhyfddh7bllbi7xszz7k9955n79-Setup.hs, /build/Main.o )
Linking Setup ...
configuring
configureFlags: --verbose --prefix=/nix/store/8115x9a12aagcijm80z270k9wxi0sihl-godot-haskell-classgen-0.1.0.0 --libdir=$prefix/lib/$compiler --libsubdir=$abi/$libname --docdir=/nix/store/dcyb58yqwr7yacwyvhy378qdkz733m1a-godot-haskell-classgen-0.1.0.0-doc/share/doc/godot-haskell-classgen-0.1.0.0 --with-gcc=gcc --package-db=/build/package.conf.d --ghc-option=-j4 --disable-split-objs --enable-library-profiling --profiling-detail=exported-functions --disable-profiling --enable-shared --disable-coverage --enable-static --disable-executable-dynamic --enable-tests --disable-benchmarks --enable-library-vanilla --disable-library-for-ghci --ghc-option=-split-sections --extra-lib-dirs=/nix/store/issgq20n7k0z2dvgdsdgijrbd7j5fqvn-ncurses-6.1-20190112/lib --extra-lib-dirs=/nix/store/b0m54d9mh38iin1qxzgq9fhvswblifjn-libffi-3.2.1/lib --extra-lib-dirs=/nix/store/lisf6nz1adrqxwx6qvvmd30lq3a068hq-gmp-6.1.2/lib
Using Parsec parser
Configuring godot-haskell-classgen-0.1.0.0...
CallStack (from HasCallStack):
  die', called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:950:20 in Cabal-2.4.0.1:Distribution.Simple.Configure
  configureFinalizedPackage, called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:460:12 in Cabal-2.4.0.1:Distribution.Simple.Configure
  configure, called at libraries/Cabal/Cabal/Distribution/Simple.hs:596:20 in Cabal-2.4.0.1:Distribution.Simple
  confHook, called at libraries/Cabal/Cabal/Distribution/Simple/UserHooks.hs:67:5 in Cabal-2.4.0.1:Distribution.Simple.UserHooks
  configureAction, called at libraries/Cabal/Cabal/Distribution/Simple.hs:178:19 in Cabal-2.4.0.1:Distribution.Simple
  defaultMainHelper, called at libraries/Cabal/Cabal/Distribution/Simple.hs:115:27 in Cabal-2.4.0.1:Distribution.Simple
  defaultMain, called at /nix/store/4mdp8nhyfddh7bllbi7xszz7k9955n79-Setup.hs:2:8 in main:Main
Setup: Encountered missing dependencies:
haskell-src-exts-sc -any

builder for '/nix/store/jqpap7jxx2y225qcpd9m4dqvqi0hdpla-godot-haskell-classgen-0.1.0.0.drv' failed with exit code 1
error: build of '/nix/store/abl0592viapajllvy8kawy4fj5rp7cpa-ghc-8.6.4-with-packages.drv', '/nix/store/jqpap7jxx2y225qcpd9m4dqvqi0hdpla-godot-haskell-classgen-0.1.0.0.drv' failed