render a slim 404 message on /api/* (#31818)

middleware/api/index.js

@@ -37,4 +37,8 @@ if (process.env.ELASTICSEARCH_URL) {
   )
 }
 
+router.get('*', (req, res, next) => {
+  res.status(404).json({ error: `${req.path} not found` })
+})
+
 export default router

tests/rendering/api.js

@@ -0,0 +1,19 @@
+import { expect, jest, test } from '@jest/globals'
+
+import { get } from '../helpers/e2etest.js'
+
+describe('general /api pages', () => {
+  jest.setTimeout(60 * 1000)
+
+  test("any /api URL that isn't found should JSON", async () => {
+    const res = await get('/api')
+    expect(res.statusCode).toBe(404)
+    expect(res.headers['content-type']).toMatch(/application\/json/)
+  })
+
+  test("any /api/* URL that isn't found should be JSON", async () => {
+    const res = await get('/api/yadayada')
+    expect(res.statusCode).toBe(404)
+    expect(JSON.parse(res.text).error).toBe('/yadayada not found')
+  })
+})