How to build opencv.js with seamlessClone

Since the seamlessClone method is not available in the officially distributed opencv.js builds, I attempted to build my own opencv.js module by following the steps mentioned here: OpenCV: Build OpenCV.js

I added ‘seamlessClone’ to the photo section in the file and was able to build it successfully. The seamlessClone method is available in the browser but if I try to use it, I get an error “6607080” without any other information. I’m not sure I’ve added everything right to get seamlessClone working.

related: javascript - How do I build opencv.js with seamlessClone? - Stack Overflow

There are no answers in that link. Can you point me to developers with experience in custom opencvjs builds?