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">


return exporter.getInvoker();
        }
        public void setExporter(Exporter<T> exporter) {
            this.exporter = exporter;
        }
        @Override
        public void unexport() {
            String key = getCacheKey(this.originInvoker);
            bounds.remove(key);
            Registry registry = RegistryProtocol.this.getRegistry(getRegistryUrl(originInvoker));
            try {
                registry.unregister(registerUrl);
            } catch (Throwable t) {
                logger.warn(REGISTRY_UNEXPECTED_EXCEPTION, "", "", t.getMessage(), t);
            }
            try {
                if (subscribeUrl != null) {
                    Map<URL, NotifyListener> overrideListeners = getProviderConfigurationListener(subscribeUrl).getOverrideListeners();
                    NotifyListener listener = overrideListeners.remove(registerUrl);
                    if (listener != null) {
                        if (!registry.isServiceDiscovery()) {
                            registry.unsubscribe(subscribeUrl, listener);
                        }
                        ApplicationModel applicationModel = getApplicationModel(registerUrl.getScopeModel());
                        if (applicationModel.getModelEnvironment().getConfiguration().convert(Boolean.class, ENABLE_CONFIGURATION_LISTEN, true)) {
                            for (ModuleModel moduleModel : applicationModel.getPubModuleModels()) {
                                if (moduleModel.getServiceRepository().getExportedServices().size() > 0) {
                                    moduleModel.getExtensionLoader(GovernanceRuleRepository.class).getDefaultExtension()
                                        .removeListener(subscribeUrl.getServiceKey() + CONFIGURATORS_SUFFIX,
                                            serviceConfigurationListeners.remove(subscribeUrl.getServiceKey()));