Enable express error handler (#4697)

* Propagate error to express handler in all situations

* Call the default error handler if `enableExpressErrorHandler` is truthy

* Updating options interface and definitions

* Testing express error handler

* Test spec fixes

* Fix test

src/middlewares.js

@@ -284,6 +284,9 @@ export function handleParseErrors(err, req, res, next) {
     res.status(httpStatus);
     res.json({ code: err.code, error: err.message });
     log.error(err.message, err);
+    if (req.config && req.config.enableExpressErrorHandler) {
+      next(err);
+    }
   } else if (err.status && err.message) {
     res.status(err.status);
     res.json({ error: err.message });