Better errors

rpc/errors.go

@@ -50,7 +50,7 @@ func (e Error) Error() string {
 	return fmt.Sprintf("jsonrpc2 error: code: %d message: %s", e.Code, e.Message)
 }
 
-func NewError(code int) Error {
+func ErrorFromCode(code int) Error {
 	if _, ok := errorMap[code]; ok {
 		return Error{
 			Code:    code,
@@ -59,3 +59,13 @@ func NewError(code int) Error {
 	}
 	return Error{Code: code}
 }
+
+func NewError(message string, code int) Error {
+	if code == 0 {
+		code = ErrUser
+	}
+	return Error{
+		Code:    code,
+		Message: message,
+	}
+}

rpc/server.go

@@ -114,7 +114,7 @@ func (r *RpcServer) callMethod(ctx context.Context, req *rpcRequest) *rpcRespons
 	if !ok {
 		return &rpcResponse{
 			Jsonrpc: version,
-			Error:   NewError(ErrCodeMethodNotFound),
+			Error:   ErrorFromCode(ErrCodeMethodNotFound),
 			Id:      req.Id,
 		}
 	}
@@ -137,7 +137,7 @@ func (r *RpcServer) callMethod(ctx context.Context, req *rpcRequest) *rpcRespons
 func WriteError(code int, enc *json.Encoder) {
 	enc.Encode(rpcResponse{
 		Jsonrpc: version,
-		Error:   NewError(code),
+		Error:   ErrorFromCode(code),
 	})
 }
 

rpc/wrapper.go

@@ -28,7 +28,7 @@ func H[RQ any, RS any](handler func(context.Context, *RQ) (RS, error)) Handler {
 	return func(ctx context.Context, in json.RawMessage) (json.RawMessage, error) {
 		req := new(RQ)
 		if err := json.Unmarshal(in, req); err != nil {
-			return nil, NewError(ErrCodeParseError)
+			return nil, ErrorFromCode(ErrCodeParseError)
 		}
 		resp, err := handler(ctx, req)
 		if err != nil {