The following shell command,

res = db.myCollection.mapReduce(m, r, { out : "dupliCiks" });

generates the error message

ns doesn't exist

Can this message be made more user-friendly? At least "namespace doesn't exist", or "collection doesn't exist". A search for ns on http://docs.mongodb.org/manual/search/?query=ns doesn't immediately help a new user understand what "ns" might stand for.