Actually, it looks like several other services (completions, references, definition) can return an undefined value but will then fail with "No content available." This is in cases where e.g. no definition is available, but should it really be considered an "error" from a services standpoint? It's making it hard to detect actual errors in large tsserver logs. Is there some reason for services to return undefined instead of an empty array (which produces no error)? CC @mjbvz @mhegazy