issue-#198 random trap message when calling unloaded proc

[Josef Templ]

while checking the issue with inloaded coroutnes reported by Robert I discovered a probably unrelated bug in the trap handler.
See https://redmine.blackboxframework.org/issues/198.

The fix is simply to avoid the uninitialized output param msg in DevDebug.GetTrapMsg.

- Josef

[Josef Templ]

I just noticed that this issue has been fixed before. I was using an older version.