Packages with `arch(wasm32)` conditionals are broken

[michaelpj]

For example the recently-uploaded concurrent-output-1.10.19: https://hackage.haskell.org/package/concurrent-output-1.10.19/concurrent-output.cabal

You get something like this:

       error: attribute 'isWasm32' missing

       at /nix/store/lpknwn212bi6728yqi29y97b7gqm9gg0-haskell-project-plan-to-nix-pkgs/cabal-files/concurrent-output.nix:38:137:

           37|           (hsPkgs."ansi-terminal" or (errorHandler.buildDepError "ansi-terminal"))
           38|           ] ++ (pkgs.lib).optional (!system.isWindows) (hsPkgs."unix" or (errorHandler.buildDepError "unix"))) ++ (pkgs.lib).optional (!system.isWasm32) (hsPkgs."terminal-size" or (errorHandler.buildDepError "terminal-size"));
             |                                                                                                                                         ^
           39|         buildable = true;

[michaelpj]

It's not clear that isWasm32 has ever existed in nixpkgs. Are we somehow generically processing the architecture and assuming that an isX attribute will exist in nixpkgs?