Seems that a return statement in a match arm (which nushell proper is fine with), is treated as invalid grammar
match ($val | describe) {
"path" | "string" => {}
_ => return
}
[2025-12-13T20:39:11Z ERROR topiary::error] × Parsing error between line 0, column 25 and line 3, column 0
╭─[standard input:1:26]
1 │ ╭─▶ match ($val | describe) {
2 │ │ "path" | "string" => {}
3 │ │ _ => return
4 │ ├─▶ }
· ╰──── (ERROR) node
╰────