How to match the node without children node?

[Freed-Wu]

For:

(ERROR) ; [1:1 - 12]
 (command) ; [1:1 - 4]
 (map) ; [1:6 - 10]
 (ERROR) ; [1:12 - 12]

, query

(ERROR) @error

will match [1:1 - 12], [1:12 - 12]. How to match the node without any children node?

TIA!