Function emit_fatal 

pub fn emit_fatal(category: &str, object: &str, message: &str)

See emit_info. Latches the sticky fatal and emits the canonical Fatal:<category>:<object> line — NEVER suppressed (see emit_record). The CALLER owns any early-exit control flow (e.g. latexml_post’s Fatal! returns its own PostError after this) — a fatal, unlike an error, needs no cap bookkeeping.