gossip: Fix bug in send_error handling

git-svn-id: https://scalaris.googlecode.com/svn/trunk@6205 71766da9-9752-0410-ab17-bfafa751c56a
gossip: revise type naming

git-svn-id: https://scalaris.googlecode.com/svn/trunk@6206 71766da9-9752-0410-ab17-bfafa751c56a