I did get an advance but I don't remember a clause about having to return any of it if I didn't earn it out. (I did earn it out, but I don't remember any expectation that I'd have to give them money back if I hadn't.) Also my memory was that it was more than $2k but it was about 10 years ago so I might be misremembering!
Fortunately, Elm has had no breaking changes for about six years!