How to use the esp-js-ui.ModuleChangeType.Error function in esp-js-ui

this.addDisposable(moduleLoadStream.subscribeWithRouter(this.router, this.modelId, (change: ModuleLoadResult) => {
                    _log.debug(`Load Change detected`, change);

                    if (change.type === ModuleChangeType.Error) {
                        _log.error(`Pre-requisite failed. Pre Req Name: ${change.prerequisiteResult.name}, Error Message: ${change.errorMessage}`);
                    } else {
                        this.splashScreen = {
                            state: SplashScreenState.Loading,
                            message: change.description
                        };
                    }
                },
                e => {