SensorHistory.getOxygenSaturationHistory returns null on fēnix 7X PRO: 13.22

yes , it always return null ,and  I already added null check. BUT in the api document, it will never be null , should I always add a null check everywhere? actually I have already added some null check where should not be , such as active history. 

ps. the  watch do have spo2 value,because I asked the owner to check it in the widget.  but it still  returns null .

Does this always return null on this product, or is this just an occasional issue? It's not necessarily a bug if it does return null, and it's a good idea to include null checks for things like this in general. We have had some reports about getOxygenSaturationHistory in the past, but I don't see any open issues at the moment.

yes, I've searched the forum and have seen your post about this, but I can't find the null value of it , because most of the watchface don't have a null check(as it supposed to never be null)so I think it's necessary to do these

I'm not sure if getOxygenSaturationHistory have ever really worked right on any real devices.  There are a number of bug reports from over the years..  Nulls, always oldest sample first, etc.