Fix typo

src/emqx_rpc.erl

@@ -33,6 +33,6 @@ filter_result(Delivery) ->
     case Delivery of 
         {badrpc, Reason} -> {badrpc, Reason};
         {badtcp, Reason} -> {badrpc, Reason};
-        Delivery1 -> Delivery1
+        _ -> Delivery
     end.