S.R.
When I was young I was simply a perfectionist so this type of thing would elicit the same response from me. My niece who is 4 now also reacts much the same way to accidents of any kind. My advice would be to let her help you clean up the mess. I know this sounds strange but it puts her in control of the situation and lets her see that it really is ok with you that it happened. Also, keep reassuring her that you aren't upset in anyway.