@@ -96,8 +96,9 @@ selectLatestVersions = Set.fromList . nubBy f2 . sortBy f1 . Set.toList
9696discoverUpdates :: String -> Version -> Hackage4Nix [Version]
9797discoverUpdates name vers = do
9898 db <- asks _hackageDb
99− let versions = DB.keys (fromJust (DB.lookup name db))
100− return (filter (>vers) versions)
99+ case DB.lookup name db of
100+ Just pkgs -> return (filter (>vers) (DB.keys pkgs))
101+ Nothing -> fail ("discoverUpdates cannot find package " ++ show name ++ " on Hackage")
101102
102103updateNixPkgs :: [FilePath] -> Hackage4Nix ()
103104updateNixPkgs paths = do