If `nix-shell <args>` fails, Stack just outputs the Nix error

[mpilgrem]

With Nix integration, Stack executes nix-shell with arguments. If the command fails, Stack does not attempt to put that error in any context.

For example, with shell.nix:

{ghc}:
with (import <nixpkgs> {});

haskell.lib.buildStackProject {
  inherit ghc;
  name = "myEnv";
  buildInputs = [ zlib glpk pcre ];
  duff;
}

The output of stack build --nix is just (coloured by Nix):

error: syntax error, unexpected ';', expecting '.' or '='
       at /home/mpilgrem/Code/Haskell/testNic/shell.nix:8:7:
            7|   buildInputs = [ zlib glpk pcre ];
            8|   duff;
             |       ^
            9| }

rather than something like:

Error: [S-1264]
       While using nix-instantiate, with arguments:
       * /home/mpilgrem/Code/Haskell/testNic/shell.nix
       * --arg
       * ghc
       * with (import <nixpkgs> {}); haskell.compiler.ghc9103
       * --argstr
       * ghcVersion
       * ghc9103
       * --show-trace

       Stack encountered the following error:

       error: syntax error, unexpected ';', expecting '.' or '='
              at /home/mpilgrem/Code/Haskell/testNic/shell.nix:8:7:
                   7|   buildInputs = [ zlib glpk pcre ];
                   8|   duff;
                    |       ^
                   9| }

Unfortunately, there is no way to obtain coloured output from Nix commands:

• Add option --color NixOS/nix#7650