Yep, I agree with Idgi. She did something wrong. In fact, an accident does not mean there is no "at fault". Just like in car accident. If someone's sleepy or distracted or staring the road blankly and ends up bumping the vehicle, even if it's a small bump, there's still someone at fault. Chi is not careful and thus she accidentally break the glass. Should she be punished? Depending on the context, I would say no. If this gets repetitive, then yes since this is both hazard and wasteful. But my point is, she is still at fault, and it's good that she apologizes. Telling her she shouldn't apologize because "it's not her fault" doesn't click well with what I seem as the perfect route.