NaN mean option

[xenct]

For this code, https://github.com/AusClimateService/plotting_maps/blob/main/acs_area_statistics.py, make there a way to cope with NaNs

eg "When I select ‘mean’ for calculating regional statistics I only get ‘nan’ for each region... It works fine for median. Do you know how I can circumvent this issue? Is there an ‘ignore nan’ argument?"