Kill the printing of "Handling" to stderr

The `"Handling " <> show e` message would get printed to the stderr of
the dap server. This resulted in thinking something was wrong in
inumerous occasions, seeing messages such as:

```
[stderr] DAP.Se
[stderr] rver/Handling:

[stderr] ghc-internal:GHC.Internal.IO.Exception
[stderr] .IOException:

<socket: 13>: Da
[stderr] ta.ByteString.hGetLine: end of file

IPE backtrac
[stderr] e:

[stderr]   DAP.Server
[stderr] .getHeaderHandle (src/DAP/Server.hs:(217,1)-(220,32))
HasCallStack backtrace:
  ioException, called at
[stderr]  libraries/ghc-internal/src/GHC/Internal/IO/H
[stderr] andle/Internals.hs:353:11 in ghc-
[stderr] internal:GHC.Internal.IO.Handle.Interna
[stderr] ls
```

(I had slightly tweaked the message to investigate what was going wrong)

When, in reality, nothing was wrong. This was an EOF exception
indicating the client had closed the connection.

However, when looking at the logs, the "Handling" was misleading (and
not easily correlated with the "Client has ended its connection below".

All in all, I don't think we should print the "Handling" at all. If an
exception is handled, it is handled. If it is not, then it gets logged
to the appropriate logger as "Unknown Exception".

Author: alt-romes

src/DAP/Server.hs

@@ -46,7 +46,7 @@ import           Network.Simple.TCP         ( serve, HostPreference(Host) )
 import           Network.Socket             ( socketToHandle, withSocketsDo, SockAddr )
 import           System.IO                  ( hClose, hSetNewlineMode, Handle, Newline(CRLF)
                                             , NewlineMode(NewlineMode, outputNL, inputNL)
-                                            , IOMode(ReadWriteMode), stderr, hPrint)
+                                            , IOMode(ReadWriteMode) )
 import           System.IO.Error            ( isEOFError )
 import           System.Exit                ( exitWith, ExitCode(ExitSuccess) )
 import           Text.Read                  ( readMaybe )
@@ -176,7 +176,6 @@ exceptionHandler logAction handle address shouldLog serverThread (e :: SomeExcep
           = logger logAction ERROR address Nothing
             $ withBraces
             $ T.pack ("Unknown Exception: " <> show e)
-  hPrint stderr ("Handling" <> show e)
   when shouldLog $ do
     dumpError
     logger logAction INFO address (Just SENT) (withBraces "Closing Connection")