respect environment is development on error message

src/app.js

@@ -142,7 +142,7 @@ app.use(require("./routes/eventsheet").router)
 app.use(function (err, req, res, next) {
   // set locals, only providing error in development
   if (err) {
-  res.locals.message = err.message;
+  res.locals.message = req.app.get("env") === "development" ? err.message : "An error has occurred";
   res.locals.error = req.app.get("env") === "development" ? err : {};
   if (typeof err === 'string' || err instanceof String) {
     err = {