[RxMoya] Fix warning for unused let
[RxMoya] Fix warning for unused let

Moya/Moya,justinmakaila/Moya,Moya/Moya,calt/Moya,Moya/Moya,justinmakaila/Moya,calt/Moya,justinmakaila/Moya,calt/Moya,ashfurrow/Moya,ashfurrow/Moya