Dubbo Version: 3.0.10
注册失败，unexport时，subscribeUrl和registerUrl此时为空，需要判断空处理。 
<img width="944" alt="image" src="https://user-images.githubusercontent.com/12670328/200469537-41a4ccb5-adda-4231-9f71-9af9fec2172d.png">


}
                            }
                        }
                    }
                }
            } catch (Throwable t) {
                logger.warn(REGISTRY_UNEXPECTED_EXCEPTION, "", "", t.getMessage(), t);
            }
            
            int timeout = ConfigurationUtils.getServerShutdownTimeout(subscribeUrl.getScopeModel());
            executor.schedule(() -> {
                try {
                    exporter.unexport();
                } catch (Throwable t) {
                    logger.warn(REGISTRY_UNEXPECTED_EXCEPTION, "", "", t.getMessage(), t);
                }
            }, timeout, TimeUnit.MILLISECONDS);
        }
        public void setSubscribeUrl(URL subscribeUrl) {
            this.subscribeUrl = subscribeUrl;
        }
        public void setRegisterUrl(URL registerUrl) {
            this.registerUrl = registerUrl;
        }
        public URL getRegisterUrl() {
            return registerUrl;
        }
    }
}