Muselet issue with AO cube
Issue reported by Felipe Barrientos (account to be created when Laure is back).
In my last cube, that has been taken with AO, step 2 is crashing because the inv_variance.fits image has only zeroes. inv_variance is created at the end of step 1 so everything is fine up to that moment. I think is related to the AO nature of these observations given they have a masked region is wavelength. I can create a inv_variance image by hand but then it crashed at the end of step 3 (I don't really know why this is).