stackgaps

Only relevant when stackgroup is used, and only the first stackgaps found in the stackgroup will be used - including if visible is "legendonly" but not if it is false. Determines how we handle locations at which other traces in this group have data but this one does not. With "infer zero" we insert a zero at these locations. With "interpolate" we linearly interpolate between existing values, and extrapolate a constant beyond the existing values.