The some HO form passes callbacks through call_sx_fn which creates a new
VM that can't see the enclosing closure's captured variables (el). Replaced
with for-each + mutation which keeps everything in the same VM scope.
Also fixed destructuring param ((verb ...)) → plain param (verb).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>