Method record_fail

crates/ffi/src/lean_env.rs:1662–1667

(&mut self, msg: String)

                  gen_ci.get_type().pretty(),
                  orig_ci.get_type().pretty(),
                );
                let gen_val_str = match &gen_ci {
                  LeanCI::DefnInfo(d) => d.value.pretty(),
                  LeanCI::ThmInfo(t) => t.value.pretty(),
                  LeanCI::RecInfo(r) => format!(
                    "<rec with {} rules>\n  rule[0].rhs: {}",
                    r.rules.len(),
                    r.rules.first().map(|x| x.rhs.pretty()).unwrap_or_default()
                  ),