Designing a watchface for different devices with different sensors

Hi,

I am trying to design a watchface which shows the current heartrate. This works pretty well for my Fenix 3 HR since it has a built in HR monitor. Nevertheless, if I want to design the watchface also for the Fenix 3 (without HR) the compiler says:

Could not find symbol getHeartRateHistory.
Symbol Not Found Error
in onUpdate


How can I design the watchface for different watches and omit the heart rate value for watches without built in sensor?

Thanks for supporting.