Macro rpc_error_obj 

macro_rules! rpc_error_obj {
    ($code:expr_2021, $message:expr_2021, $data:expr_2021) => { ... };
    ($code:expr_2021, $message:expr_2021) => { ... };
}

Create a JSON-RPC error object (not a response)

Usage:

// Error with code and message
rpc_error_obj!(error_codes::INVALID_PARAMS, "Invalid parameters")

// Error with code, message and data
rpc_error_obj!(error_codes::INVALID_PARAMS, "Invalid parameters", {"expected": "array"})