🎨 error improvements (#7600)

* ✨  id for each error instance
- copy paste of ignition
- on purpose for now
- delete TODO, wohoo
- use id property instead of uid, see http://jsonapi.org/format/#errors

* 🕵🏻  remove TODO for decouple req.err
- can't find a nicer alternative solution
- added some more descriptions to code pieces in our error-handler

* 🎨  use uuid.v1
- timestamp based

core/server/errors.js

@@ -1,4 +1,5 @@
 var _ = require('lodash'),
+    uuid = require('node-uuid'),
     util = require('util');
 
 function GhostError(options) {
@@ -14,11 +15,11 @@ function GhostError(options) {
 
     /**
      * defaults
-     * @TODO: I'd like to add the usage of an individual ID to errors, as we have in ignition
      */
     this.statusCode = 500;
     this.errorType = 'InternalServerError';
     this.level = 'normal';
+    this.id = uuid.v1();
 
     /**
      * custom overrides

core/server/middleware/error-handler.js

@@ -51,8 +51,7 @@ _private.parseStack = function parseStack(stack) {
 /**
  * Get an error ready to be shown the the user
  *
- * @TODO: support multiple errors
- * @TODO: decouple req.err
+ * @TODO: support multiple errors within one single error, see https://github.com/TryGhost/Ghost/issues/7116#issuecomment-252231809
  */
 _private.prepareError = function prepareError(err, req, res, next) {
     if (_.isArray(err)) {
@@ -74,7 +73,10 @@ _private.prepareError = function prepareError(err, req, res, next) {
         }
     }
 
+    // used for express logging middleware see core/server/app.js
     req.err = err;
+
+    // alternative for res.status();
     res.statusCode = err.statusCode;
 
     // never cache errors
@@ -86,7 +88,7 @@ _private.prepareError = function prepareError(err, req, res, next) {
 };
 
 _private.JSONErrorRenderer = function JSONErrorRenderer(err, req, res, /*jshint unused:false */ next) {
-    // @TODO: jsonapi errors format ?
+    // @TODO: jsonapi errors format (http://jsonapi.org/format/#error-objects)
     res.json({
         errors: [{
             message: err.message,