added an error check

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1446749 13f79535-47bb-0310-9956-ffa450edef68
no longer remove nonexistent examples

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1446750 13f79535-47bb-0310-9956-ffa450edef68