Display error descriptions

src/Main.hs

@@ -6,6 +6,7 @@ module Main
     ( main
     ) where
 
+import Control.Exception (Exception(..), handle)
 import Data.Char (isNumber)
 import Data.List.NonEmpty (NonEmpty(..))
 import Control.Monad.Catch (MonadThrow(..))
@@ -20,7 +21,6 @@ import SlackBuilder.Update
 import qualified Toml
 import Data.Text (Text)
 import qualified Data.Text as Text
-import qualified Data.Text.IO as Text.IO
 import Control.Monad.Trans.Reader (ReaderT(..))
 import SlackBuilder.Package (PackageDescription(..))
 import qualified SlackBuilder.Package as Package
@@ -28,6 +28,13 @@ import Text.URI.QQ (uri)
 import Data.Foldable (for_, find)
 import GHC.Records (HasField(..))
 import System.Process (CmdSpec(..))
+import System.Console.ANSI
+    ( setSGR
+    , SGR(..)
+    , ColorIntensity(..)
+    , Color(..)
+    , ConsoleLayer(..)
+    )
 
 autoUpdatable :: [PackageDescription]
 autoUpdatable =
@@ -294,17 +301,20 @@ check = for_ autoUpdatable go
         >>= mapM_ checkUpdateAvailability
         >> liftIO (putStrLn "")
 
-
 main :: IO ()
 main = do
     programCommand <- execParser slackBuilderParser
     settings <- Toml.decodeFile settingsCodec "config/config.toml"
-    latestVersion <- flip runReaderT settings
+    handle handleException
+        $ flip runReaderT settings
         $ runSlackBuilderT
         $ executeCommand programCommand
-
-    maybe (pure ()) Text.IO.putStrLn latestVersion
   where
+    handleException :: SlackBuilderException -> IO ()
+    handleException slackBuilderException
+        = setSGR [SetColor Foreground Dull Red]
+        >> putStrLn (displayException slackBuilderException)
+        >> setSGR [Reset]
     executeCommand = \case
-        CheckCommand -> check >> pure Nothing
-        Up2DateCommand packageName -> up2Date packageName >> pure Nothing
+        CheckCommand -> check
+        Up2DateCommand packageName -> up2Date packageName