Fix minor issues

src/errors/emgauwa_error.rs

@@ -139,7 +139,7 @@ impl Serialize for EmgauwaError {
 	{
 		let mut s = serializer.serialize_struct("error", 2)?;
 		s.serialize_field("code", &self.get_code().as_u16())?;
-		s.serialize_field("description", &String::from(self))?;
+		s.serialize_field("message", &String::from(self))?;
 		s.end()
 	}
 }