Kill the printing of "Handling" to stderr

[alt-romes]

    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".

[alt-romes]

@dmjio would you like to take a look?

This has caused me so much confusion! Only now I properly realized that this gets printed always!!
We should kill it.

[dmjio]

Yea that looks problematic. Killing it is fine with me.