remove unused variable

src/Util.rsc

@@ -18,7 +18,7 @@ set[Message] syntaxErrors(M3 model) =
 // All error messages that occurred during loading of the model
 set[Message] modelErrors(M3 model) =
   { e
-  | e:error(msg, _) <- model.messages
+  | e:error(_, _) <- model.messages
   };
 
 // Assumption: the given identifier has exactly one name.