another situation that causes the command in progress error

already-in-progress-2.hs

module Lib
    ( someFunc
    ) where
import Control.Monad
import Data.Int
import Data.Monoid
import Data.Functor.Contravariant

import Hasql.Connection
import Hasql.Session
import Hasql.Query
import qualified Hasql.Decoders as HD
import qualified Hasql.Encoders as HE

someFunc :: IO ()
someFunc = void $
  acquire "postgres://j@localhost:5432/demo1" >>= \case
    Left err -> error $ show err
    Right c -> do
      print =<< run txSum c
      run (sql "RAISE division_by_zero;") c
      print =<< run txSum c

txSum :: Session Int64
txSum = do
  sql "begin;"
  s <- query (1,1) selectSum
  sql "end;"
  return s

selectSum :: Query (Int64, Int64) Int64
selectSum =
  statement sql encoder decoder True
  where
    sql = "select ($1 + $2)"
    encoder =
      contramap fst (HE.value HE.int8) <>
      contramap snd (HE.value HE.int8)
    decoder =
      HD.singleRow (HD.value HD.int8)