error message when use proxy.. "*** Exception: Network/HTTP/Client/Manager.hs:(334,9)-(336,45): Non-exhaustive patterns in case"

gistfile1.hs

{-# LANGUAGE DeriveGeneric     #-}
{-# LANGUAGE OverloadedStrings #-}

import Network.Connection (TLSSettings (..))
import Network.HTTP.Conduit
import Network.HTTP.Types.Status
import qualified Data.ByteString.Char8 as B
import qualified Data.Text as T
import Data.Time.Clock
import Data.Time.Calendar
import qualified Control.Exception as E
import qualified Data.ByteString.Lazy as L

past :: UTCTime
past = UTCTime (ModifiedJulianDay 56200) (secondsToDiffTime 0)
 
future :: UTCTime
future = UTCTime (ModifiedJulianDay 562000) (secondsToDiffTime 0)
 
cookie :: Cookie
cookie = Cookie { cookie_name = "password_hash"
               , cookie_value = "abf472c35f8297fbcabf2911230001234fd2"
               , cookie_expiry_time = future
               , cookie_domain = "vul.jp"
               , cookie_path = "/"
               , cookie_creation_time = past
               , cookie_last_access_time = past
               , cookie_persistent = False
               , cookie_host_only = False
               , cookie_secure_only = False
               , cookie_http_only = False
               }

getSomething :: IO L.ByteString
getSomething = do
    let url = "https://vul.jp/"
    request' <- parseUrl url
    let settings = mkManagerSettings (TLSSettingsSimple True False False) Nothing
    let request = request' 
                { cookieJar = Just $ createCookieJar [cookie] 
                , method = "POST"
                , secure = True
                }
    let req = addProxy "localhost" 10000 request
    eitherResp <- E.try (withManagerSettings settings $ httpLbs req)
    case eitherResp of
      Left (StatusCodeException s _ _)
        | statusCode s == 403 -> return "login failed."
        | statusCode s == 404 -> return "Dose not exist."
        | otherwise         -> return ""
      Right resp -> return (responseBody resp)

main = do
    body <- getSomething
    print body

ghci$:load gistfile1
[1 of 1] Compiling Main             ( gistfile1.hs, interpreted )
Ok, modules loaded: Main.
ghci$ main 
*** Exception: Network/HTTP/Client/Manager.hs:(334,9)-(336,45): Non-exhaustive patterns in case