cv2.error: OpenCV(4.2.0) C:\projects\opencv-python\opencv\modules\imgproc\src\canny.cpp:829: error: (-215:Assertion failed) _src.depth() == CV_8U in function 'cv::Canny' 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