Added help & ghostErrorCode properties to API errors

- This is initial ground work to enable us to do a full error audit
- We want to prevent Ghost admin from ever showing any unhandled errors
- Additionally we want to ensure all handled errors are well worded & have context+help

core/server/web/shared/middlewares/error-handler.js

@@ -77,8 +77,10 @@ _private.JSONErrorRenderer = (err, req, res, next) => { // eslint-disable-line n
         errors: [{
             message: err.message,
             context: err.context,
+            help: err.help,
             errorType: err.errorType,
-            errorDetails: err.errorDetails
+            errorDetails: err.errorDetails,
+            ghostErrorCode: err.ghostErrorCode
         }]
     });
 };