Plug space leaks when processing multiple files

shellcheck.hs

@@ -225,7 +225,7 @@ runFormatter sys format options files = do
     f :: Status -> FilePath -> IO Status
     f status file = do
         newStatus <- process file `catch` handler file
-        return $ status `mappend` newStatus
+        return $! status `mappend` newStatus
     handler :: FilePath -> IOException -> IO Status
     handler file e = reportFailure file (show e)
     reportFailure file str = do