Macro rpc_error 

macro_rules! rpc_error {
    ($code:expr, $message:expr, $id:expr) => { ... };
    ($code:expr, $message:expr) => { ... };
}

Create an error response with code, message, and optional ID

Usage:

// Error with explicit code, message and ID
rpc_error!(-32602, "Invalid parameters", Some(1))

// Error with code and message, ID from variable
rpc_error!(-32602, "Invalid parameters", id)

// Error without ID
rpc_error!(-32601, "Method not found")

// Error using predefined error codes
rpc_error!(error_codes::INVALID_PARAMS, "Invalid parameters", id)