extern crate cfg_if; cfg_if::cfg_if! { // When the `console_error_panic_hook` feature is enabled, we can call the // `set_panic_hook` function to get better error messages if we ever panic. 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() {} } }