index/kv.js:394:9B-399: yaml = f.yaml === true || codeOf(key) === null makes
the following code === null throw impossible — yamlCode never returns
null. The user-facing "not a meta key … pass yaml:true" refusal can never
print, and a mistyped meta key silently switches to the YAML lane instead of
being rejected (BEE-024 keyed lane). Found in the 2026-08-21 review.
Order the tests so an unknown key without yaml:true refuses again; unit
repro asserting the refusal text.
yaml:true opts in