Honor Error.status(Code) in handle-errors middleware (github#17768)

* Honor error status codes in handle-errors

* Add a test

middleware/handle-errors.js

@@ -37,6 +37,12 @@ module.exports = async function handleError (error, req, res, next) {
       .send(await liquid.parseAndRender(layouts['error-404'], req.context))
   }
 
+  // If the error contains a status code, just send that back. This is usually
+  // from a middleware like `express.json()` or `csrf`.
+  if (error.statusCode || error.status) {
+    return res.sendStatus(error.statusCode || error.status)
+  }
+
   if (process.env.NODE_ENV !== 'test') {
     console.error('500 error!', req.path)
     console.error(error)

tests/rendering/server.js

@@ -1,6 +1,6 @@
 const lodash = require('lodash')
 const enterpriseServerReleases = require('../../lib/enterprise-server-releases')
-const { get, getDOM, head } = require('../helpers/supertest')
+const { get, getDOM, head, post } = require('../helpers/supertest')
 const { describeViaActionsOnly } = require('../helpers/conditional-runs')
 const path = require('path')
 const { loadPages } = require('../../lib/pages')
@@ -114,6 +114,13 @@ describe('server', () => {
     expect($.res.statusCode).toBe(500)
   })
 
+  test('returns a 400 when POST-ed invalid JSON', async () => {
+    const res = await post('/')
+      .send('not real JSON')
+      .set('Content-Type', 'application/json')
+    expect(res.statusCode).toBe(400)
+  })
+
   test('converts Markdown in intros', async () => {
     // example from markdown source in intro:
     // The `git rebase` command