helper Error::bad_arg method

src/error.rs

@@ -66,6 +66,13 @@ impl Error {
         }
     }
 
+    pub fn bad_arg(func: Option<&str>, arg_index: i32, arg_name: Option<&str>, error: Arc<Self>) -> Self {
+        let func = func.map(|s| s.to_string());
+        let arg_name = arg_name.map(|s| s.to_string());
+
+        Self::BadArgument { func, arg_index, arg_name, error }
+    }
+
     /// Throw the error in lua.
     /// 
     /// This method never returns