So I have this property initialization:
this.currentMapObject$ = zip(this.mapObjects$, this.currentMapObjectsIndex$,
(mapObjects, index) => mapObjects[index]);
I only want to emit this.currentMapObject$ if this.currentMapObjectsIndex$ emits but not if this.mapObjects$ emits.
As far as I know now this.currentMapObject$ will emit even if a single property of an item of this.mapObjects$ changes. I want to ignore all changes to this.mapObjects$ and only take its current value, but I DO want to react to this.currentMapObjectsIndex$ changes