Streaming response not streaming all values

Given the following server, if I connect with `curl` I only see `true`, `false`. I expect to see `true`, `false`, `true`. The logging in the program does indicate that both `False` and a second `True` are sent (using `yieldMany`).

```haskell
{-# language TypeApplications #-}

module Main where

import Servant
import Servant.Server
import RIO
import qualified Network.Wai.Handler.Warp

type API = StreamGet NewlineFraming JSON ( StreamGenerator Bool )

main :: IO ()
main = Network.Wai.Handler.Warp.run 8080 $ serve ( Proxy @API ) $ do
chan <- newTChanIO
traverse_ ( atomically . writeTChan chan ) [ True, False, True ]

return $ StreamGenerator $ \yieldFirst yieldRest -> do
atomically ( readTChan chan ) >>= yieldFirst

forever $ do
msg <- atomically ( readTChan chan )
putStrLn ( " !!!!! " <> show msg )
yieldRest msg
putStrLn "OK"
```