Qlik Sense Extension get right Object Id in all Situations (vanilla, master item, story)

getObjectId.ts

function getObjectId(scope: any): Promise<string> {
    return new Promise((resolve, reject) => {
        try {
            let objectId: string = "";
            if (scope.layout.sourceObjectId) {
                // story
                objectId = scope.layout.sourceObjectId;
                scope.component.model.app.getObject(objectId)
                .then( ( obj: EngineAPI.IGenericObject ) => {
                    obj.getProperties()
                    .then( ( props: EngineAPI.IGenericProperties ) => {
                        if (props.qExtendsId)  {
                            // extension as master item
                            objectId = props.qExtendsId;    
                        }
                        resolve(objectId);
                    })
                    .catch( ( error ) => {
                        console.error( error )
                        reject(error);
                    });
                })
                .catch( ( error ) => {
                    console.error( error )
                    reject(error);
                });
            } else {
                // normal extension or extension as master item
                objectId = scope.layout.qExtendsId ? scope.layout.qExtendsId : scope.layout.qInfo.qId;
                resolve(objectId);
            }
        } catch (error) {
            console.error(error);
            reject(error);
        }    
    });
}