Duplicated error messages

[marcellussiegburg]

When running the Interpreter error messages occur twice.

For instance considering the following file Test.hs.

module Test where
import Prelude

main :: IO ()
main = do hSetBuffering stdout NoBuffering
         putStr "This leads to an error"

When calling the interpreter within the terminal in the following way:

$ stack ghci
Using main module: 1. Package `test' component exe:test-exe with main-is file: /private/tmp/test/app/Main.hs
Building all executables for `test' once. After a successful build of all of them, only specified executables will be rebuilt.
test-0.1.0.0: configure (lib + exe)
Configuring test-0.1.0.0...
test-0.1.0.0: initial-build-steps (lib + exe)
The following GHC options are incompatible with GHCi and have not been passed to it: -threaded -O2
Configuring GHCi with the following packages: test
GHCi, version 8.6.5: http://www.haskell.org/ghc/  :? for help
[1 of 2] Compiling Lib              ( Lib.hs, interpreted )
[2 of 2] Compiling Main             ( /private/tmp/test/app/Main.hs, interpreted )
Ok, two modules loaded.
Loaded GHCi configuration from /private/var/folders/0k/rhm0fs9j0m9g0syf1rh5nmx40000gn/T/haskell-stack-ghci/56899571/ghci-script
*Main Lib> :set -package hint
package flags have changed, resetting and loading new packages...
Prelude> :m +Language.Haskell.Interpreter
Prelude Language.Haskell.Interpreter> :{
Prelude Language.Haskell.Interpreter| compiler :: MonadInterpreter m => [String] -> m ()
Prelude Language.Haskell.Interpreter| compiler modules = do
Prelude Language.Haskell.Interpreter|   set [installedModulesInScope := False]
Prelude Language.Haskell.Interpreter|   loadModules modules
Prelude Language.Haskell.Interpreter|   setTopLevelModules modules
Prelude Language.Haskell.Interpreter| :}
Prelude Language.Haskell.Interpreter> runInterpreter (compiler ["Test"])

The response contains the (correct) error message duplicated:

Left (WontCompile [GhcError {errMsg = "Test.hs:5:8: error:\n    Unexpected do block in function application:\n        do hSetBuffering stdout NoBuffering\n    You could write it with parentheses\n    Or perhaps you meant to enable BlockArguments?"},GhcError {errMsg = "Test.hs:5:8: error:\n    Unexpected do block in function application:\n        do hSetBuffering stdout NoBuffering\n    You could write it with parentheses\n    Or perhaps you meant to enable BlockArguments?"}])