fix error condition

lib/expressapp.js

@@ -508,12 +508,8 @@ ExpressApp.prototype.start = function(opts, cb) {
         ts: +req.query.ts,
       };
       server.getFiatRate(opts, function(err, rates) {
-        if (err) returnError({
-          code: 500,
-          message: err,
-        });
+        if (err) return returnError(err, res, req);
         res.json(rates);
-        res.end();
       });
     });
   });