return the right output dir on failure

src/Argonix.hs

@@ -358,7 +358,7 @@ setupSystem target sa = do
 
   when (isTarget target) $ setupNodeOs envVars
 
-  return (envVars, varXDG_CACHE_HOME)
+  return (envVars, varTMPDIR)
  where
   getVars :: [Text] -> IO [(Text, Text)]
   getVars vars = catMaybes <$> mapM maybeGet vars
@@ -409,7 +409,7 @@ nixArguments target ArgsCommon {..} =
 wrap :: NixCommand -> Text -> ArgsCommon -> IO ()
 wrap nixCommand target sa@ArgsCommon {..} = do
   when (verbosity == Verbose) $ print sa
-  (envVars, tmpXDGHOME) <- setupSystem target sa
+  (envVars, tmpDir) <- setupSystem target sa
   putText $ nixc <> " " <> T.unwords arglist
   case nixCommand of
     NixShell -> executeFile (toS nixc) True (fmap toS arglist) Nothing
@@ -421,7 +421,7 @@ wrap nixCommand target sa@ArgsCommon {..} = do
         >>= \case
               ExitSuccess -> copySuccess "/tmp/papa"
               ExitFailure _ ->
-                copyFailure (toS tmpXDGHOME) >> die "build failed."
+                copyFailure (toS tmpDir) >> die "build failed."
  where
   copySuccess source =
     runProcessVerbose verbosity "cp" ["-r", source, "./result"] []