When passing a JSON object with no params, I get the following message returned with the JSON:

"warning: ksort() expects parameter 1 to be array, null given in [modules folder]/jsonrpc_server\/JsonRpcServer.php on line 158.\"

It doesn't seem to break the functionality, as data is still returned, but it does add extra data to the JSON response which isn't good. Adding a check to ensure that $this->args is an array before doing the ksort() would probably solve this.