Error when try running the code

[Pretip]

When i try to run the program it shows this error - line 28, in
image = cv2.resize(frame, (0, 0), None, ratio, ratio) # resize image
cv2.error: OpenCV(4.5.1) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-wvn_it83\opencv\modules\imgproc\src\resize.cpp:4051: error: (-215:Assertion failed) !ssize.empty() in function 'cv::resize'

How to fix this? Pls help