piff_des/tests/run_data_fits.py fails to read psf from config.yaml file

[areshernandez]

run_data_fits.py runs into some trouble when attempting to read the config.yaml file. Specifically, I copied this file from "/nfs/slac/g/ki/ki18/cpd/Projects/piff_des/configs/des_optatmo.yaml" and only changed its name from "des_optatmo.yaml" to "config.yaml." It seems to run into trouble when trying to read the use_gradient boolean. Is "use_gradient" a new feature in config.yaml? If so, is there something in psf.py that needs to be changed to work properly with it?

Traceback (most recent call last):
  File "tests/run_data_fits.py", line 243, in <module>
    run(**kwargs)
  File "tests/run_data_fits.py", line 108, in run
    psf = piff.PSF.process(config['psf'], logger=logger)
  File "/u/ec/aresh/Piff-wavefront/piff/psf.py", line 82, in process
    psf = cls(**kwargs)
TypeError: __init__() got an unexpected keyword argument 'use_gradient'