cv2.error: OpenCV(4.1.0) /home/pi/opencv-4.1.0/modules/imgproc/src/resize.cpp:3718: error: (-215:Assertion failed) !ssize.empty() in function 'resize in raspberry pi code example

Example: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

This error happened because the image didn't load properly.
So you have problem with the previous line cv2.imread my suggestion is :

check if the images exist in the path you give

check the count variable if he have valid number