You've certainly got a bit of a dilemma there! This is difficult to answer without knowing more about the nature of the coworker, your relationship with her, and her motivation behind the gesture. Is she for example a neophyte cook, making her first curry and requiring constructive criticism. In my experience it's most unusual to find bones in curry, and saltiness is very much a matter of personal preference. It's certainly a challenge in diplomacy for you - good luck.