Happy days, yesterday we updated form 16.3 to 16.4 and thanks to them fixing the bug in 'getDerivedStateFromProps' my broken code is now breaking.

Don't you just love it when features inadvertently depend on bugs. The entire component ONLY worked properly because of a react bug.

Sounds like you originally raped a react concept to bring up your feature ;)

Imagine having to modernise a whole product and move it from C++ to C# and in the process test it properly for the first time ever.

Oh, and by the way, some of the bugs in the C++ version are relied on by clients now, so you better make sure they’re replicated.

I had to build a heuristic comparison tool that sat in the build pipeline that could run both versions and kinda eyeball the output and guess at whether they were tolerably close to each other.

Its the last step of debugging: "How did that ever work!?"
I once had my broken code only work if I uncommented a console.log
It didnt even care what was in it, I just had to log SOME string for the code to work.