我有以下与OpenCV 3.4.1配合使用的代码，现在无法与OpenCV 4.1.0配合使用并给出了错误。我不知道如何用新版本适应代码，您能帮我吗？非常感谢

def ImageProcessing(image):
    image = cv2.absdiff(image, background)
    h, gray = cv2.threshold(image, 65, 255, cv2.THRESH_BINARY_INV);
    gray = cv2.medianBlur(gray,5)

    kernel = np.ones((3,3), np.uint8)

    gray = cv2.erode(gray, kernel, iterations=1)#1

    des = cv2.bitwise_not(gray)
    tmp = cv2.findContours(des,cv2.RETR_CCOMP,cv2.CHAIN_APPROX_SIMPLE)
    contour, hier = tmp[1], tmp[0]

    for cnt in contour:
        cv2.drawContours(des,[cnt],0,255,-1)

    gray = cv2.bitwise_not(des)

    gray = cv2.dilate(gray, kernel, iterations=1)#1

    return gray

错误是

cv2.error：OpenCV（4.1.0）/io/opencv/modules/imgproc/src/drawing.cpp:2509：错误：（-215：断言失败）函数’drawContours’中的npoints>
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