The program does not work in raspberry autorun, what should I do?

Question

Python

In general, the problem of launching a program with video output. The beginning of the program is successful, that is, the script itself works, but when you try to output the video, an error occurs. Photos of logs and a test program are attached

Prog:

import cv2
import numpy as np
import cv2 as cv
print ("Hello World!")
cap = cv2.VideoCapture(0)
cap.set(cv.CAP_PROP_FRAME_WIDTH, 320) 
cap.set(cv.CAP_PROP_FRAME_HEIGHT, 240)
while True:
    flag, img = cap.read()
    cv2.imshow('img', img)
    ch = cv2.waitKey(5)

Interaction with raspberry happens through VNC Viewer