/**
     * Called when an error occurs during processing.
     *
     * @param phase the phase where the error occurred
     * @param error the error message
     */
    void onError(String phase, String error);

    /**
     * Returns a no-op callback implementation.
     *
     * @return a callback that does nothing
     */
    static ChatPhaseCallback noOp() {

     */
    void onChunk(String chunk, boolean done);

    /**
     * Called when an error occurs during streaming.
     *
     * @param error the error that occurred
     */
    default void onError(final Throwable error) {
        // Default implementation does nothing
    }

                        }
                    }
                }

                @Override
                public void onError(final String phase, final String errorCode) {
                    try {
                        sendSseEvent(writer, "error", Map.of("phase", phase, "message", errorCode, "errorCode", errorCode));

            callback.onError("llm", e.getErrorCode());
            throw e;
        } catch (final Exception e) {
            logger.warn("[RAG] Unexpected error during enhanced chat. sessionId={}, error={}, elapsedTime={}ms", session.getSessionId(),
                    e.getMessage(), System.currentTimeMillis() - startTime, e);
            callback.onError("unknown", LlmException.ERROR_UNKNOWN);
            throw e;

                }
            } catch (ex) {}

            handleError(thinkingId, messageElement, errorMessage);
            eventSource.close();
        });

        eventSource.onerror = function() {
            if (!state.errorHandled) {
                handleError(thinkingId, messageElement, config.labels.error);
            }
            eventSource.close();
        };