pub fn structured_export_error(vars: &[(String, Value)]) -> Option<String>Expand description
Reject exporting a structured value into an OS env var. A list/record can’t
cross the process boundary, and kaish will not silently JSON-serialize it into
the child’s environment. Returns a loud “serialize first” message naming the
offending variable, or None if every exported value is a scalar. Both
external-spawn sites (kernel.rs, dispatch.rs) call this before cmd.env.