Trying to build ocaml-lsp

shell.nix

let
    pkgs = import <nixpkgs> {};
    cinaps = pkgs.ocaml-ng.ocamlPackages_4_09.buildDunePackage rec {
        pname = "cinaps";
        version = "latest";

        src = pkgs.fetchFromGitHub {
            owner  = "ocaml-ppx";
            repo   = "cinaps";
            rev    = "e3183c4733d0577d4d54211cafa4a52dfe5dd235";
            sha256 = "0kd7y81d3d1rjlh4gjk8faa3i5qrgviavhf1y9vmrn8z5njiy86c";
        };

        buildInputs = [ 
            pkgs.ocaml-ng.ocamlPackages_4_09.re 
        ];
    };
    ppx_yojson_conv_lib = pkgs.ocaml-ng.ocamlPackages_4_09.buildDunePackage rec {
        pname = "ppx_yojson_conv_lib";
        version = "latest";

        src = pkgs.fetchFromGitHub {
            owner  = "janestreet";
            repo   = "ppx_yojson_conv_lib";
            rev    = "bcc43bec7b37c4770348082d207fe208f7b22d0d";
            sha256 = "1df8wbjlb71rvwz2zcw882vsav5czkp3xy4qxc1ldppm66sybjhi";
        };

        buildInputs = [ 
            pkgs.ocaml-ng.ocamlPackages_4_09.yojson 
        ];
    };
    ocaml-lsp = pkgs.ocaml-ng.ocamlPackages_4_09.buildDunePackage rec {
        pname = "lsp";
        version = "latest";

        ocaml = pkgs.ocaml-ng.ocamlPackages_4_09.ocaml;

        minimumOCamlVersion = "4.06.1";

        src = pkgs.fetchgit {
            url = "https://github.com/ocaml/ocaml-lsp";
            sha256 = "0jlh6zxrdcnfdbici2gwwk4j83hb2fvlnf285wpcbdwh08w14afa";
            fetchSubmodules = true;
        };

        useDune2 = true;

        buildInputs = [ 
            pkgs.ocaml-ng.ocamlPackages_4_09.merlin
        ];
        propagatedBuildInputs = [ 
            pkgs.ocaml-ng.ocamlPackages_4_09.yojson
            ppx_yojson_conv_lib 
            pkgs.ocaml-ng.ocamlPackages_4_09.stdlib-shims
            pkgs.ocaml-ng.ocamlPackages_4_09.menhir
            pkgs.ocaml-ng.ocamlPackages_4_09.cmdliner
            cinaps
        ];
        doCheck = false;

        preInstall = ''
            make lsp-server
        '';
    };
in
    pkgs.mkShell {
        buildInputs = [
            pkgs.ocaml-ng.ocamlPackages_4_09.ocaml
            pkgs.opam
            pkgs.dune_2
            ocaml-lsp
            pkgs.opam
        ];
    }