Function env_usize

crates/ffi/src/kernel.rs:2108–2113

(var: &str, default: usize)

    Ok(env) => env,
    Err(e) => {
      return LeanIOResult::error_string(&format!(
        "rs_env_extract: failed to deserialize {path}: {e}"
      ));
    },
  };
  // Resolve displayed names → addresses through the full env's `named`
  // metadata (the anon view discards it). Keys and requests both go
  // through `normalize_displayed_name` (Lean `«»`-escaped ↔ Rust bare).
  let by_name: FxHashMap<String, Address> = full