use cfg_if::cfg_if; cfg_if! { // https://github.com/rustwasm/console_error_panic_hook#readme if #[cfg(feature = "console_error_panic_hook")] { extern crate console_error_panic_hook; pub use self::console_error_panic_hook::set_once as set_panic_hook; } else { #[inline] pub fn set_panic_hook() {} } }