SNES client error in autofocus

In the SNES client main.py line 32:

ret = requests.post(BASE_URI + "/extensions/org.openflexure.autofocus/fast_autofocus", json={'dz':1000, 'backlash':250})

it's necessary to remove 'backlash':250, otherwise the program aborts. Also according with William's suggestion it would be better to replace 1000 y 2000.