fetchItchIo: fix SSL error and improve missing envvar message (#498540)

{

  lib,

  stdenvNoCC,

  cacert,

  python3,

}:

        outputHashAlgo = if finalHashHasColon then lib.head finalHashColonMatch else null;

        outputHashMode = "flat";

        nativeBuildInputs = [ python3 ] ++ nativeBuildInputs;

        nativeBuildInputs = [

          cacert

          python3

        ]

        ++ nativeBuildInputs;

        inherit preferLocalBuild;

import platform

import shutil

import sys

import urllib.error

import urllib.parse

import urllib.request

    print(message, file=sys.stderr)

    sys.exit(1)

try:

    API_KEY = os.environ[ENV['apiKeyVar']]

except KeyError:

API_KEY = os.environ.get(ENV['apiKeyVar'])

if not API_KEY:

    abort(

        f'Either set {ENV['apiKeyVar']} for the nix building process '

        f'Error: Either set the environment variable {ENV['apiKeyVar']} '

        '(for the nix-daemon in multi user mode) '

        f'or manually download {ENV.get('uploadName', 'the required file')} '

        f'from {GAME_URL} and add it to nix store.'

        f'from {GAME_URL} and add it to the nix store.'

    )

def urlopen(url_or_request):