Possible null reference return.

Nullability of reference types in type of parameter 'sender' of 'void PerformanceMonitorBase.SamplingTimer_Elapsed(object sender, ElapsedEventArgs e)' doesn't match the target delegate 'ElapsedEventHandler' (possibly because of nullability attributes).

Dereference of a possibly null reference.

Dereference of a possibly null reference.

Nullability of reference types in type of parameter 'sender' of 'void PerformanceMonitorBase.SamplingTimer_Elapsed(object sender, ElapsedEventArgs e)' doesn't match the target delegate 'ElapsedEventHandler' (possibly because of nullability attributes).

Non-nullable field 's_systemPerformanceMonitor' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Possible null reference return.

Possible null reference return.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.