fix bug with empty result and non table result

internal/server/rpc/responsers.go

@@ -25,6 +25,12 @@ func NewError(code int, message string, data any, id *json.RawMessage) *RPCRespo
 }
 
 func NewResponse(result any, id *json.RawMessage) *RPCResponse {
+	if result == nil {
+		return &RPCResponse{
+			JSONRPC: JSONRPCVersion,
+			ID:      id,
+		}
+	}
 	return &RPCResponse{
 		JSONRPC: JSONRPCVersion,
 		ID:      id,

internal/server/rpc/writers.go

@@ -28,7 +28,7 @@ func write(nid string, w http.ResponseWriter, msg *RPCResponse) error {
 	msg.Salt = generateSalt()
 	if msg.Result != nil {
 		msg.Checksum = generateChecksum(msg.Result)
-	} else {
+	} else if msg.Error != nil {
 		msg.Checksum = generateChecksum(msg.Error)
 	}