What a search that found nothing says: the text it looked for (`under` a namespace), and, when that's text with characters a regular expression would have (`a|b`), that it was taken as written: a regular expression is written `/…/`.
A pattern is its text as written, or a regular expression written /…/ with its flags; text is matched in or out of case as asked, a written regular expression as its flags say; and what finding nothing says names which it was.
A pattern as tcm's text searches take it (`tcm search`, `tcm view --grep`, the agent tools', code search in an editor): the text as written (`a|b` is that text), or a regular expression written `/…/`, flags after it (`/get|set/i`). `regex` takes all the text as a regular expression, without slashes (an editor's toggle, and `tcm search --regex`, the old way). `caseSensitive` is for text and a regular expression without slashes: one written `/…/` matches case as its `i` flag says. `wholeWord` keeps to matches that are whole words. `find` gives a line's matches, as [start, end); a regular expression that isn't one is an `error`.