Move Error to separate module

nand2tetris.cabal

@@ -29,6 +29,7 @@ library
   hs-source-dirs:      src
   default-language:    Haskell2010
   exposed-modules:     Nand2Tetris.Hack
+                     , Nand2Tetris.Error
   build-depends:       base >= 4.7 && < 5
                      , text
                      , megaparsec

src/Nand2Tetris/Error.hs

@@ -0,0 +1,14 @@
+
+module Nand2Tetris.Error
+  (
+    Error(..)
+  ) where
+
+import qualified Data.Text as T
+import Text.Megaparsec.Error (ShowErrorComponent (showErrorComponent))
+
+data Error = ParsingError T.Text Int
+  deriving (Show, Eq, Ord)
+
+instance ShowErrorComponent Error where
+  showErrorComponent = show