如果mime类型无效，如何在busboy中停止上传和重定向？

I am fairly new to Node.js, and I am using Express and Busboy-Connect to create a simple file upload form, for wav files only. Here is what I am trying to do : - start the upload - if the mimetype is not wav, redirect to an error page - else : write the file on the server and redirect back.I am fairly new to Node.js, and I am using Expr