e isn't used to prefix with _

src/macros.rs

@@ -53,7 +53,7 @@ macro_rules! try_send {
 	($i:ident, $e:expr, $($arg:tt)*) => {
 		match $e {
 			Ok(r) => r,
-			Err(e) => {
+			Err(_e) => {
 				return SendQueue(vec![($i, std::fmt::format(format_args!($($arg)*)), true)].into());
 				}
 			}