Use BoxError in on error cases

src/apps.js

@@ -1996,7 +1996,7 @@ function uploadFile(appId, sourceFilePath, destFilePath, callback) {
 
     const done = once(function (error) {
         safe.fs.unlinkSync(sourceFilePath); // remove file in /tmp
-        callback(error);
+        callback(new BoxError(BoxError.FS_ERROR, error.message)); // blame it on filesystem for now
     });
 
     // the built-in bash printf understands "%q" but not /usr/bin/printf.