scanner: lower logging level on uncatch exceptions

    ''' Create a function that takes a single argument -- an error from a

    measurement -- and return that function so it can be used by someone else

    '''

    def closure(err):

        log.error('Unhandled exception caught while measuring %s: %s %s',

                  target.nickname, type(err), err)

    def closure(object):

        # The only object that can be here if there is not any uncatched

        # exception is stem.SocketClosed when stopping sbws

        log.debug(type(object))

    return closure