That would remove 1 data member, but it seems like API is not as clean. This would lead to:

```
        if (popoverState.marker) {
            popoverState.marker.clear();
            
            $previewContent.empty();
            $previewContainer.hide();
            $previewContainer.removeClass("active");
        } else {
```

So I didn't change it. Let me know if you feel strongly about it.