How to fix error of properties of null (reading, 'width')

Question

https://code.sololearn.com/WIk3RMHGPkqT/?ref=app
I get that error how do I fix please check...

Answer 1

#webCam

Not

#webcam

Answer 2

JavaScript is case-sensitive, so these IDs must match exactly. As A͢J has pointed out. #webCam and #webcam, must be the same.