Should catch reject promise of close client.

[summer-ji-eng]

rpc method can't catch error of rejected promise
(node:98660) UnhandledPromiseRejectionWarning: The client has already been closed.

canceller = toCall(argument, (err, response, next, rawResponse) => {
               ...
            }).catch(err => {
                console.log('---canceller error: ', err)
                callback(err);
            });
            ```

[summer-ji-eng]

fixed