title: I couldn't get past this error in open cv
body: <pre><code>cv2.error: OpenCV(4.4.0) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-2b5g8ysb\opencv\modules\highgui\src\window.cpp:376: error: (-215:Assertion failed) size.width&gt;0 &amp;&amp; size.height&gt;0 in function 'cv::imshow'
  </code></pre>