Route Flags load warnings to stderr

src/HomeAssistant/Runtime/Flags.hs

@@ -24,6 +24,7 @@ import Data.Set (Set)
 import qualified Data.Set as S
 import Data.Text (Text)
 import System.FilePath ((</>))
+import System.IO (hPutStrLn, stderr)
 import System.IO.Error (isDoesNotExistError)
 
 type Name = Text
@@ -56,7 +57,7 @@ readFlagsFile path =
     decoded <- decodeFileStrict' path
     case decoded of
       Nothing -> do
-        putStrLn ("handlers.json is unparseable; treating all handlers as enabled: " <> path)
+        hPutStrLn stderr ("handlers.json is unparseable; treating all handlers as enabled: " <> path)
         pure mempty
       Just m -> pure (maybe mempty id m)
   where
@@ -64,7 +65,7 @@ readFlagsFile path =
     onMissingOrUnreadable e
       | isDoesNotExistError e = pure mempty
       | otherwise = do
-          putStrLn ("could not read handlers.json (" <> show e <> "); treating all handlers as enabled")
+          hPutStrLn stderr ("could not read handlers.json (" <> show e <> "); treating all handlers as enabled")
           pure mempty
 
 isEnabled :: MonadIO m => Flags -> Name -> m Bool