proposed fix for wolframclient error

error.py

from PIL import Image
import io
from wolframclient.language import wlexpr, wl
from wolframclient.evaluation import WolframLanguageSession
import numpy as np

def CurvatureFlowFilter(session, img):

    data = session.evaluate(wl.CurvatureFlowFilter(img, 50))

    z = session.evaluate(wl.ExportByteArray(data, "PNG"))

    im = np.array(Image.open(io.BytesIO(z)))

    return im


def Binarize(session, img):
    data = session.evaluate(wl.Binarize(img))

    z = session.evaluate(wl.ExportByteArray(data, "PNG"))

    im = np.array(Image.open(io.BytesIO(z)))

    return im

img = Image.open('/Users/rdv/Desktop/59380297_10156593903528155_315272697133137920_o.jpg')

with WolframLanguageSession() as session:

    bin_img = Binarize(session, img)
    print(bin_img)
    curv_img = CurvatureFlowFilter(session, img)
    print(curv_img)