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/Options/Definitions.js

@@ -262,6 +262,12 @@ module.exports.ParseServerOptions = {
     "action": parsers.booleanParser,
     "default": false
   },
+  "enableExpressErrorHandler": {
+    "env": "PARSE_SERVER_ENABLE_EXPRESS_ERROR_HANDLER",
+    "help": "Enables the default express error handler for all errors",
+    "action": parsers.booleanParser,
+    "default": false
+  },
   "objectIdSize": {
     "env": "PARSE_SERVER_OBJECT_ID_SIZE",
     "help": "Sets the number of characters in generated object id's, default 10",

src/Options/index.js

@@ -114,6 +114,8 @@ export interface ParseServerOptions {
   cacheMaxSize : ?number; // = 10000
   /* Use a single schema cache shared across requests. Reduces number of queries made to _SCHEMA. Defaults to false, i.e. unique schema cache per request. */
   enableSingleSchemaCache: ?boolean; // = false
+  /* Enables the default express error handler for all errors */
+  enableExpressErrorHandler: ?boolean; // = false
   /* Sets the number of characters in generated object id's, default 10 */
   objectIdSize: ?number; // = 10
   /* The port to run the ParseServer. defaults to 1337.

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 });