FileNotFoundError in VsCode Flask

I am new to python and flask on vsCode, and I have decided to run a py file given on github. https://github.com/kaushikjadhav01/COVID-19-Detection-Flask-App-based-on-Chest-X-rays-and-CT-Scans However when i run the py file, the html part seems to be working except for the part where I have to upload an x ray image. The system produces a FileNotFoundError: [Errno 2] No such file or directory: ‘./flask app/assets/images\upload_chest.jpg’.

The code is too long to be inserted here however u can view the link given above to see the code. it is called app.py