front-end can't decode protobuf message with type int32 when encoded bytes'length is more than 1 byte

"connector.entryHandler.enter": {
        "required int32 code": 1,
        "optional double serverTime": 2,
        "optional string session": 3
    }
and we act like this:    next(null, {code: 200,session:'aaabbbb'});
the 200 can't be resolved corrected;