server: handle unexpected exceptions on connect: `classname` attribute was used on exceptions while it may not exists with some of them. This patch fixes this by showing a warning and re-raising the exception when this case happens.

The work in this directory is licenced under a MPL/GPL/LGPL tri-license:
    - MPL 1.1
    - GPL 2 or later
    - LGPL 2 or later

Originally distributed by the Mozilla Foundation
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