Why does WARN crash when working with a camera in OpenCV, Python?

Question

Python

There is a code that scans a QR code:

import cv2
import numpy as np
import pyzbar.pyzbar as pyzbar

cap = cv2.VideoCapture(0)

while True:
    _, frame = cap.read()

    decodedObjects = pyzbar.decode(frame)
    for obj in decodedObjects:
        print("Data", obj.data)

    cv2.imshow("Frame", frame)

    key = cv2.waitKey(1)
    if key == 27:
        break

Everything is working. It is necessary to make a function from this code that will return the first value received. When you try to change the line to to, the following is printed: [ WARN:0] global C:\projects\opencv-python\opencv\modules\videoio\src\cap_msmf.cpp (674) SourceReaderCB ::~SourceReaderCB terminating async callback continues to work (does not crash), but no other code after the line of calling the resulting function is executed. What to do to fix this // suggest an alternative to make a function out of this. PS Directory C:\Projects\opencv-python\opencv\... not found on drive C:\ print("Data", obj.data)return obj.data

Answer 1

1) So you use return outside of the function? And what are you waiting for, except for an error?
2) Check the success of the returned result, and only then process the frame:

ret, frame = cap.read()
if ret:
    ...